Talk:PCI Express

External

Blackmagic Design's Multibridge Extreme appears to implement external PCIe. The device itself is housed in a 1U rackmount and cabled to a card comprising nothing but a 4-lane PCIe edge connector wired to what looks very much like a DVI connector. It's visible on their website:

http://www.blackmagic-design.com/products/multibridge/

Whether this puts the lie to the "External: No" part of the page, or whether this is an unofficial application, it's clear that someone has implemented external PCIe.

The Multibridge Extreme is a device that uses PCIe to connect to the computer. The card that it uses is not simply a card that creates "External PCIe" It is an adapter for the use of Blackmagic Design. Jvc3po 17:51, 15 February 2007 (UTC)

Old/Unititled Conversations

I removed the information that Apple use MXM in their new iMac 24" and only use PCIe in their Powermac line of computers. While interesting for a Mac-user, it's quite pointless information in this article. 81.233.73.177/Jonas

PCI-Express is not, however, fast enough to be used as a memory bus.

First, I think you mean FSB (or some chipset to chipset bus, similiar to the Intel Hub interface, or the PCI bus which glues the North and South bridges together), not "memory bus." The memory bus is handled by the Noth bridge or Memory Hub controller. Secondly, a "high-bandwidth configuration with 8 lanes allowing 8 bits to be sent direction simultaneosly would allow up to 2,000MBps bandwith (each way)..." Also "future increases in signaling speed could increase that to 8,000MBps each way over the same 40 pins." "It...can also be used to replace the existing Intel hub architecture, HyperTransport, and similiar high-soeed interfaces between motherboard chipset components." In light of this information, I don't believe the case that PCI-Express is not "fast enough" for FSB/chipset to chipset communications(?) is supportable.

• Quotes taken from Scott Mueller's Upgrading and Repairing PCs, 15th Anniversary Edition, Chapter 4, Types of I/O Buses, page 333

--MSTCrow 06:31, Jun 22, 2004 (UTC)

Apple's running a 1.25Gbps/line x 64 line bus in their latest G5's, which due to overhead and ping-ponging, delivers about 20GBps continual. That is to say the current on-market machines already outperform the theoretical performance of not-yet-existing versions of PCI-X by almost 3x. HyperTransport is even more effected by this speed issue, as it is only offered as a backplane bus, whereas PCI-X has a future as a PCI replacement (maybe, we'll see). Generally though my statement is clearly supportable even today.

Maury 12:10, 22 Jun 2004 (UTC)

When you say PCI-X, you mean PCI-Express, and not PCI-X, right? PCI-X is another PCI-based bus, apart from PCI-Express.

--MSTCrow 16:25, Jun 23, 2004 (UTC)

Yeah, sorry, my bad short form! Maury 12:04, 24 Jun 2004 (UTC)

pic request

It would be nice if the article had photos of some pci-x devices, i.e. are the connectors similar to PCI?

There are plenty of pictures in the documents at pcisig.com. You could perhaps pick something out and ask their permission to include them if you really want one, but I'm going on to write an article on dielectric loss budgets. Dennis 21:31, 14 Jan 2005 (UTC)

I think this user meant photos of PCIe devices. The connectors are visually simillar and phyiscally incompatible. --Cmiyc 01:36, 3 August 2006 (UTC)

Non Tech Question

Much goodie techie stuff here, but what about putting a PCI-e card in a PCI slot, does that work ? regards a Non techie geek

As stated later on, PCIe and PCI/PCI-X are not mechanically compatible. Their physical layers (electrically) are completely different.--Cmiyc 01:36, 3 August 2006 (UTC)

Why is the article's name PCI-Express?

Why is the article's name PCI-Express? PCI SIG uses only PCI Express in its website, this article uses both spellings. --Jannex 09:10, 28 Feb 2005 (UTC)

Googling around, it seems that PCI Express is the most accepted spelling, so the title and the use in the article should be changed. Thue | talk 13:20, 28 Feb 2005 (UTC)

I changed it. Somebody should go through the pages listed at [1] and correct the usage. Thue | talk 00:10, 2 Mar 2005 (UTC)

I've fixed them all. Left notices in discussions where needed. Glad to assist. ^demon 2:43, March 3, 2005 (UTC)

"vast majority of new computers PCI Express capable"

I remove the sentense

The vast majority of new computers from both Intel and AMD are PCI Express capable.

from the article. A visit to the website of my local computer store tells me that this is not yet the case. Thue | talk 8 July 2005 12:59 (UTC)

Um, your local computer store has nowhere near the volume of an OEM such as Dell, HP, etc. (Local shops also tend to lag on newer products. Kind of like how walmart STILL sells nVidia 5200s.) Hence, using it as the basis for PCI Express marketshare is totally baseless. Back on topic, I do believe all the OEMs have pretty much made the switch. So, unless you or anyone else can give a link or show otherwise, that statement should be re-inserted.the1physicist 8 July 2005 17:32 (UTC)

Well, this is rather seriously offtopic for a page about PCI-express, but I don't consider Wal-Mart to be a choice place for parts of any sort, especially for computers; it's more in the league of an office store: emergency parts only. If you're referring to Nvidia FX5200 cards, they're perfectly capable for 99.5% of machines anyway, so nobody cares. Fsiler 03:36, 5 November 2005 (UTC)

My local computer shop has quite a high throughput, so it is not _that_ out-dated. Anyway, I checked out Dell and HP's websites. A survey of 6 Dell PCs showed that all of them had PCI-ex graphic card support. A survey of 6 HP PCs (their HP pavillion line) showed that half of them had PCI graphics card support. NONE of the computers had any other PCI-ex slots apart from the graphics one! Based on this quick survey I will agree that PCI-ex seems to be taking over the graphics slot, but not even starting to replace standard PCI slots yet; I would not call a motherboard unqualified "PCI express capable" with only one PCI-ex slot which is taken by the graphics card. The 75% of motherboard which had a graphics card PCI-ex slot also does not justify the formulation "vast majority", even ignoring that they had no generel-purpose PCI-ex slots. Thue | talk 9 July 2005 06:34 (UTC)

Ok, here's where your argument breaks down. A motherboard does _not_ have to be fully PCI Express to be considered PCI Express capable. That statement is true even if it's mostly just for graphics right now. And actually, most PCI-E motherboards *do* have one or two x1 slots, even if they're not being used. Anyhow, I suppose I retract the word "vast", but the majority of new computers do have some form of PCI Express.the1physicist 9 July 2005 07:37 (UTC)

In my book it is misleading to say that a motherboard is "PCI express capable" when only the graphics slots are PCI express; reading that I would expect them to have at least one free generel-purpose PCIe slot. None of the 12 systems I checked out had any 1x PCIe slots! We can however say in the article that "the majority of systems seems to have a PCIe slot for graphics". Thue | talk 9 July 2005 07:44 (UTC)

Alrighty then. You do know that you can plug a x1 card in to a 16X slot, right? Not to mention that most motherboards with 16X slots usually have 1-2 1x slots. You seem to have gotten unlucky or something.the1physicist 9 July 2005 10:07 (UTC)

Hot pluggability?

On pinouts.ru, the PCI Express pinout has some hot-plug detect pins. Is PCI Express hot-pluggable? And if it is, why? Mrdelayer~ 10:20, 15 July 2005 (UTC)

I believe they were planning on making a cable specification. Something like USB, but better.the1physicist 15:56, 15 July 2005 (UTC)

For servers and other high-up time systems. --Cmiyc 01:36, 3 August 2006 (UTC)

Card/slot combinations

What card/slot size combinations are possible? For example, can an x4 card be plugged into an x16 slot? Can an x8 card be plugged into an x4 slot?

I believe that with PCI, a 32-bit card could be plugged into a 64-bit slot, and a 64-bit card could (at least in some cases) be plugged into a 32-bit slot (it would just operate at the lower bandwidth). What are the comparable possibilities for PCI Express?

I hoped to find an answer to this question here, so presumably others may also.

--Beric 14:38, 26 July 2005 (UTC)

You can't overhang the cards like you can with PCI, but you can install lower speed cards into faster slots (and the rest of the pins are [of course] unused). So, you could put a x1 or x4 into your x16 slot if you wanted.

-Dan November 14, 2005

i was looking for this info, too. it appears you can, based on a 2004 test by Tom's (see link i added at bottom of link section (altho it may be a special/nonavailible BIOS). also, an ASRock Core 2 mobo either has just a x4 slot or a x16 slot that only runs at x4. i was curious to see if it was even worth considering it and that's the info my first 30 seconds of websearching turned up. looks to be "acceptable" at least up to a 6800 Ultra. not sure about higher... Plonk420 21:04, 17 August 2006 (UTC)

General Compatibility

I'd heard that PCI-E is "backwards compatible" with PCI. When I got my new computer with PCI-E, I wanted to keep one of my old PC cards, but it would not physically fit: the PCI-E slots have a space between the pins near the panel side that the PCI card I wanted to keep didn't have a matching gap for, so it could not go in the slot. However, I checked some of my other PCI cards, and some of them did have that gap and did fit. Now, I want to buy a new card (USB2 & Firewire), but the only PCIe cards available so far cost a lot, and I'm fine with a PCI card (speedwise), but since my old one didn't fit, how can I tell if a new one will fit? I'm not looking for someone to directly answer my questions on Wikipedia, I can find a forum for that. It's just that there's no section addressing compatibility with PCI cards, I expected to get some info on this here, if anyone could add it.

-Tom, June 6, 2006

PCI-E is NOT backwards compatible with PCI PERIOD, the software layers may be the same but the physical interface is totally different. BTW the intro to this article reads rather like a marketing peice. Plugwash 23:11, 15 June 2006 (UTC)

This is exactly the question I came looking for, as a confused owner of 4 pci-e slots. Someone who understands this stuff enough to be writing about it should add this info and an explanation as to why to the main article. -Josh March07

Practically speaking if you want to use those slots you will have to find PCI express cards that give you the functions you want. Soloutions do exist that will let you connect pci cards through a pci-e slot (see for example http://www.magma.com ) but you will have to pay through the nose for them.

BTW be carefull not to confuse pci-e with pci-x (as it looks like the initial poster of this section may have done) Plugwash 21:59, 25 March 2007 (UTC)

Performance Difference

Is there really noticible (higher than 5%) performance difference between PCI-e and AGP graphics card? I have used both versions of 6600GT and I cannot notice any difference even though the bridging chip should slightly slow it down. --Antilived 11:01, 6 August 2005 (UTC)

For the most part, there is little to no performance penalty for AGP. I do believe that a PCI-E 8X will be about 2% slower than 16X, and a 4X about 5% slower than a 16X.the1physicist 22:11, 6 August 2005 (UTC)

This is application-dependant. PCIex does have much less latency and overhead for small transactions. On an application doing lots of small texture updates (google for "uberflow" to have an example) the PCIex machine ended up being 80% faster than the AGP one on similar hardware! 83.176.117.138 08:03, 31 July 2006 (UTC)

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[[User:|User:]] 14:38, 28 October 2005 (UTC)

Looking at the Specfications for the TYAN Tomcat i7230A, it claims to have 2 PCIe x16 slots. One with x8 Signal and one with x4 signal. What does this mean?

There's three different speeds - card, slot, and signal. As long as the card is <= the slot speed, it will work. However, all of the slots could have less signal lines so they're really slower than expected. However, I don't know exactly where the difference is (perhaps in the bridge chip??). -Dan November 14, 2005

---

PCI-X is merged with the PCI article. Suggest that this be merged with the PCI article, too? --BleachInjected 02:56, 4 November 2005 (UTC)

• I'd* have to say no, because unlike PCI-X (which was an extension of PCI), this is different physically. It's serial and has dedicated channels. It's designed to be compatable with PCI programming (only requiring a new transport), but it's not electrically similar.

-Dan November 14, 2005

article language

This is by no means a criticism of the PCIe specification -- merely a reminder that PCIe is not exempt to the rules of a layered packet protocol, no more so than other comparable high-speed serial technologies (such as Serial ATA and Fibre Channel). It seems to me this language doesn't belong in an encyclopedia article. How about (This is not an issue peculiar to the PCI express interface.) If nobody complains, I'll change it. Feel free to revert (with discussion).

Help with 'conversion'

"As it is based on the existing PCI system, cards and systems can be converted to PCI Express by changing the physical layer only – existing systems could be adapted to PCI Express without any change in software." Does this mean a PCI slot can support a PCI-express card? Or do you have to have a PCI-express slot that could possibly support an older PCI card? I'd like to get a new video card, but the one I want is PCI-Express, while I only have PCI-X slots. EDIT: I think they're PCI-X slots, but I'm not completely sure on if they are or how to find out. PirateMonkey 02:18, 28 January 2006 (UTC)

The slots are not compatible in any way. I presume the new PCIe slots were designed to make it impossible to insert old PCI cards. That section is simply saying that there needs to be no change in the software interface. Makers of PCI cards/chips can make a PCIe version by changing the physical interface and the card will work in a PCIe system. The system still sees a host bridge, one or more buses behind it, and devices with vendor:device ID's. No massive change to the way that works, except for graphics cards moving from AGP. Imroy 06:05, 28 January 2006 (UTC)

I just spotted some stuff at http://www.mobl.com/expansion/products/pcie_expansion/index.html for using PCI cards with a PCIe system, they are bloody expensive though. Plugwash 12:01, 12 March 2007 (UTC)

HowStuffWorks article

I've read on howstuffworks in article about PCI next:

“ PCI-Express slots will also accept older PCI cards, which will help them become popular more quickly than they would if everyone's PCI components were suddenly useless. ”

How can it be true? Or may be that article too old? PCIe slots are completely different from PCI - or I'm mistaking? If my motherboard have both PCI & PCIe stots - is it mean that all PCI slots - are PCIe slots but with PCI-formfactor ? Or motherboard have 2 different buses PCI & PCIe ? And PCI slots will be works as usual with bus multiplexing ? — Preceding unsigned comment added by 81.200.2.184 (talk • contribs)

That information is just wrong. The slots are different, and the electrical interface is *very* different. Many (most?) motherboards with PCIe slots also have legacy PCI slots as well. It's also possible the author of that information was confusing PCIe with PCI-X.

Imroy 09:51, 30 March 2006 (UTC)

PCI Express

Please  wikipedia

 In   Hardware   level.   Talk me  in   bit  or  bits   or   b.
  
 In   Software   level.   Talk me  in   BYTE  OR  BYTES  or  B.

 No confusion for  final  user, PLEASE !
  

 or   always   b =   bit(s)    and  B  =  BYTE(S)

PEG ≡ PCI Express

Is PEG (PCI-Express For Graphics) 100% identical with normal PCIe or not? --Hhielscher 01:05, 16 April 2006 (UTC)

PEG == PCI Express Graphics. It is 100% identical, but is specifically called PEG because the slots sit directly off of the northbridge/MCH, so they have less latency for memory and CPU cycles. The regular PCI Express slots sit off the southbridge, and there's extra latency in communicating upstream to the northbridge. Rmcii 20:09, 13 May 2006 (UTC)

PCI Express 2.0 Specification

Does anyone have a soild source regarding the upcoming PCI Express 2.0 specification? Most notably the expected final release date and the added hardware support for virtualization in this new standard?

I'm missing information on the PCIE 1.0a spec. What is different for 1.0a?

What is newer, 1.0 or 1.0a? What does it mean for a graphics card to be 1.0a compliant?

adaptors

i guess an adaptor could theoretically be made to fit a card into a smaller slot then intended but there would be physical issues with the machines case in doing so. Would that be a correct analysis? Plugwash 23:15, 15 June 2006 (UTC)

Yes that would be correct. The added height would cause physical problems. There are companies that make "shims" to convert to lower lane widths. They are useful for testing.

got any names of such companies? a quick googling doesn't seem to be finding any. Plugwash 20:14, 17 January 2007 (UTC)

Outlook

The article says "As of 2006, PCI Express appears to be well on its way to becoming the new backplane standard in personal computers." However, since each PCI Express lane stands alone (as contrasted to the shared 32 or 64bit bidirection pins of regular PCI), it doesn't appear to match the definition of backplane given. I suggest that this be revised to "As of 2006, PCI Express appears to be well on its way to becoming the new internal expansion standard in personal computers." JDBoyd 13:49, 09 Aug 2006 (EST)

The article says that as of 2005 it looks like PCI-E may become the standard for PC's. Well it's half past 2006 and I think PCI-E has indeed become the standard for PC's. Anyone agree? Dionyseus 21:49, 14 July 2006 (UTC)

Its certainly dominated all other newcomers (PCI-X agp etc) but afaict its still got some way to go to kill off PCI as the dominiant general purpose expansion slot system. Plugwash 02:25, 26 August 2006 (UTC)

BW/clock

Where is the bandwidth and clock info? I believe this should be pointed out somewhere. 83.176.117.138 08:05, 31 July 2006 (UTC)

This question doesn't really make sense to me. What clock info? The bit rate is 2.5Gbit/s. The reference clock is 100MHz. There are sources on the actual bandwidth, after you account for some of the overhead and 8b/10b encoding.

I suppose his/her question is this (and it's also the same question I have): how does the reference clock affect the bandwidth, if at all? There's no info anywhere on this that I can see, and I think it would be highly valuable to people who want to know how overclocking the PCI-E clock affects overall speed, etc... The documentation for CPUs, AGP cards, and so on is so obvious, but I can't find the data anywhere for PCI Express cards. Does anyone here know the answer?

250 MiB or 250 MB

It is definitely 250 MB/s.
It's 1.25GHz * 2 bits/clock / (10 bits/byte) = 250 million bytes per second = 250 MB/s
To quote the IBM Redbook (see Link in the article):

"The 8b/10b encoding essentially requires 10 bits per character, or about 20% channel overhead. This encoding explains differences in the published spec speeds of 250 MBps (with the embedded clock overhead) and 200 MBps (data only, without the overhead)."

And especially to DmitryKo: If 2.5 Gbit/s was the real data bandwdith, you'd get 298 MiB/s and not 250 MiB/s.
I hope that's proof enough for you. If not, please show me how to get 250 MiB/s with a clock of 1.25GHz, DDR and a 8b/10b encoding. In my opinion, this is a calculation you should have done before changing the MB to MiB.
JogyB 21:22, 27 August 2006 (UTC)

• I just didn't realize bus bandwidth is expressed in decimal units... sorry. --Dmitry _{(talk •contibs )} 06:22, 28 August 2006 (UTC)

Nothing said above really matters, since some retardo has erroneously changed all the units to megabits, when they clearly should be bytes. The article which is cited as source 1 does talk about bits, but it is also wrong in doing so. — Preceding unsigned comment added by 84.248.78.243 (talk • contribs)

It looks like the intro was already reverted the change from bytes to bits, i have now removed the dubious reference that caused that change in the first place. Plugwash 20:44, 2 February 2007 (UTC)

An issue that could be added: Operating System Support

My research shows that older Window OS's -- 95, 98, Me, NT4 -- won't run on systems with PCI Express. And Win2K may have problems.— Preceding unsigned comment added by 75.6.242.35 (talk • contribs)

Where have you run into this? Do you mean drivers like video cards? One of the advantages of PCIe is that the hardware and BIOS can "hide" the implementation so that the software just sees PCI like it has since the 90s. — RevRagnarok ^{Talk Contrib} 11:06, 6 September 2006 (UTC)

Most newer chipsets which support PCIe do not have drivers or any manufacturer support for older OSes including 98, NT, or ME. — Preceding unsigned comment added by 166.68.134.174 (talk • contribs)

splitting

is it feasible to have a splitter card that plugs into one PCI-E slot and routes different lanes to different cards? Plugwash 15:37, 2 December 2006 (UTC)

I assume not. A "link" is made of one or more "lanes", and the data is interleaved when a link has more than one lane. So I'm thinking it simply wouldn't make sense to split one link into its constituent lanes and use them separately. It would be like splitting up the 32 bits in the original PCI bus. Those bits/lanes are meant for one device. Perhaps you're thinking of a bridge? --Imroy 18:08, 2 December 2006 (UTC)

No, it is not a bus in the traditional way. You can do some magic with interrupt lines and use a bus expander card on standard PCI, but PCI Express is a whole different beast. For all effective purposes, it is a point to point protocol. — RevRagnarok ^{Talk Contrib} 15:04, 3 December 2006 (UTC)

I take that back. A "non-passive" card with an active PCI Express hub chipset may be able to do it, similar to a USB hub. But you would be limited by the "upstream" bandwidth so would need a x16 slot to handle two x8 peripherals. I'm not sure about addressing either, the downstream cards would have to split an address space. May get quite ugly, but probably possible - you'd have to pay me a lot to design one. ;) — RevRagnarok ^{Talk Contrib}

hmm, at what stage are the lanes on a host controller assigned to links? does it happen at chip design time? bios design time? or is it discovered at boot time? the last possibility would allow splitter cards. Plugwash 20:07, 8 January 2007 (UTC)

As for addressing wouldn't an active splitter card just appear as a PCI-PCI bridge with a new bus number for the slots behind it? Plugwash 17:59, 9 March 2007 (UTC)

Amount of lanes?

Is there any limit on how many lines a motherboard board can have? I saw a motherboard that has 3 PCIe 16x slots, 3x16 is 48 lanes total. -- Frap 07:58, 8 December 2006 (UTC)

The number of lanes on a motherboard is implementation-specific. They're only limited by the number of pins that can be crammed onto a chip package (another good reason to go serial), and by the ability to connect multiple chips together. There are large enterprise-level machines with many individual PCI buses (yes, buses, not slots) - I believe one use is to stuff them full of SCSI cards to access truly huge RAID arrays or tape archive units with many drives being fed my robotic tape handlers. Exactly the same thing could be done with PCIe. The only issue is how to connect so many buses and processors together. These large machines are very much like supercomputers with high-speed interconnects tying everything together. Anyway no, there is almost no limit on the number of lanes on a motherboard. --Imroy 09:20, 8 December 2006 (UTC)

Hotplugging

i see someone changed yes to no in the infobox for hotplugging and was reverted, the body text has no mention of this issue, so four questions.

• does PCI express support hotplugging?
• is support for it required or is it some obscure optional part of the spec?
• is support for it in major operating systems?
• how does this tie in with its software compatibility with PCI? —The preceding unsigned comment was added by Plugwash (talk • contribs) 15:17, 29 December 2006 (UTC).

As far as I know:

• Yes, it does.
• It depends on the form factor; for the common card form factor, it's optional (it needs extra hardware on the slot).
• I know Linux supports it; a quick google search shows Windows also seems to support it.
• PCI also has hotplug; I have no idea if an older OS which does not understand PCI Express would be able to work with its hotplug.

--cesarb 01:07, 2 February 2007 (UTC)

Speed Negotiation

I heard that a given slot is only required to support its own number of logical lanes, and 1 Lane-- but nothing in between. For instance, if you have a 16x slot and put a 8x card into it, there is no guarantee it will link at 8x, it very likely will link at 1x.

I'm looking to confirm/deny this and find some way to mention it in the article as it can be a big issue for AV and throughput intensive apps. — Preceding unsigned comment added by 12.106.16.98 (talk • contribs)

AGP

according to our AGP article the fastest variant of AGP that is listed has a maximum data rate of 2133 megabytes per second. PCIe after taking account of 8b10b encoding but not of higher level overheads (which is the figure most comparable with the headline figures for older paralell busses) with 8 lanes runs at 2000 megabytes per second. That sounds close enough to me. Plugwash 13:41, 16 January 2007 (UTC)

Now if there was an AGP 16x that would change things but i'm pretty sure there isn't Plugwash 13:48, 16 January 2007 (UTC)

Hot Plug Footnote

The standard footnote tag is not functioning properly with symbols, or the table messes it up. - MSTCrow 00:47, 2 February 2007 (UTC)

Hotplugging

Why is the table currently listed as hotpluggable depending on form factor? PCI-Express is always hotpluggable. How easy it is to actually access the card for removal or insertion is another issue altogether. - MSTCrow 03:28, 2 February 2007 (UTC)

AFAIK, when it's using the traditional card form factor, whether it's hotpluggable or not depends on extra hardware on the slot (the presentation I added to the external links has the details). That hardware is not always present. I also do not know whether the PCI Express Mini Card is hotpluggable or not. (Of course, if someone does have access to the actual standards, feel free to correct me.) --cesarb 14:51, 2 February 2007 (UTC)

Well, try this, a book everyone should have on their shelves (if not, go buy it). Scott Mueller's Upgrading and Repairing PCs, 17th Edition, Chapter 4, page 376, second to last bullet. - MSTCrow 00:15, 4 February 2007 (UTC)

But what the heck is it?

This opening paragraph is all fine and good...

PCI Express... is an implementation of the PCI connection standard that uses existing PCI programming concepts, but bases it on a completely different and much faster full duplex, multi-lane, point to point serial physical-layer communications protocol. PCI Express was formerly known as Arapaho or 3GIO for 3rd Generation I/O.

but it's lacking on what what the heck PCI Express actually is. (I mean, I personally know, but I fear readers unfamiliar with the finer aspects of computer hardware will not). The rest of the article is rather confusing also. I added an "unclear" tag. Hopefully someone with greater knowledge than myself can clear this up for the mortals. Sloverlord 01:25, 7 February 2007 (UTC)

I have attempted to to so. The articel still needs help, especially as it starts to describe things (EG. "lanes") well before it goes into details of what they are. 68.39.174.238 15:06, 10 February 2007 (UTC)

Missing/Incomplete info in Sidebar

I was comparing the various bus systems (ISA, PCI, AGP, PCI-X, PCI-E) and all but PCI-E has "Width:" and "Speed:" defined. Even if PCI-e (or is it PCIe) has multiple values for these fields, could they not all be listed to provide conformity with the other bus sidebars? Maetrix 17:52, 14 March 2007 (UTC)

First things first PCI express is not a bus, neither is AGP for that matter. PCI express is based on point to point serial links with an encoding that embeds the clock not on a paralell set of data lines with seperate control lines. Plugwash 20:33, 15 March 2007 (UTC)

That is clearly noted in the article, but it's still called a bus. — RevRagnarok ^{Talk Contrib} 01:23, 16 March 2007 (UTC)

pointless overuse of jargon

As an independent IT consultant of a great many years, I get a little tired of keeping up to date with the latest developments and latest acronyms.

Wiki, on the whole has proved to be an invaluable reference source on any number of subjects and serves primarily to clarify more complex concepts for the average reader who has no background in a given specialised field.

I read that this article has been criticised as being unclear. I agree wholeheartedly. It is written by a technical expert for comprehension only by other technical experts who are conversant in the latest set of acronyms and technologies.

I have read articles within Wiki's bounds about extremely complex subjects such as can be found within the general doomain of molecular biology and the quality and expertise of the author of the article has been so good that I have been able to understand the rather obtuse subject matter.

This article on the other hand serves only to make what is a fundamentally straightforward concept utterly confusing, but manages to dazzle the reader with more jargon and buzz-words per sentence than any article I have ever read on any computing related matter. In other words I believe the article was written to impress, not to clarify anything whatsoever, certainly not for a 'lay' reader. Furthermore I found the article unbelievably boring. It was like eating a diet of undercooked bread with nothing on it - stodge and more stodge, and had to give up reading halfway through because my head hurt from mentally translating all various jargon words and concepts which had been dragged in to the 'explanation'.

I believe that the purpose of Wiki is to make technically specialised subjects comprehensible to a person who has no specialisation within the given field. By this reckoning I believe the article is overdue for a complete replacement or alternate. I'll see what I can do also. Aethandor 11:27, 3 April 2007 (UTC)aethandor

a few revisions

The opening paragraph was somewhat unapproachable and it went downhill from there. I have revised it to try to make it a bit clearer. I moved the reference to development names to the bottom of the opening section as it serves only to confuse (like those people who insist on coming up with 'did you know that....' asides) when presented right at the outset of the article.

The original article dived into to talking about PCIe 1.1 without making any reference to standards bodies (PCI-SIG) or any reference to where the '1.1' had suddenly come from and I have added a section to provide this information before it is otherwise referred to.

The initial opening paragraph mentioning bridging but implied PCI to PCIe bridging (but conversely made no reference to SLI) which is wrong and I have removed this incorrect information.

To be honest much of the opening section is still hard to chew and it would read better if written with a view to explaining to ones' Grandmother rather than writing in a style of trying to justify oneself to Bill Gates. Phrases such as "PCIe is a flexible hybrid serial-parallel interface format.", "it uses serial interconnects which can be arbitrarily linked together" and "PCI Express is both full duplex and point to point" seem to take glee from the complexity and perversity of the concepts which aren't really being explained. I will look further into clarifying these if no-one else beats me to it. —The preceding unsigned comment was added by Aethandor (talk • contribs) 14:08, 3 April 2007 (UTC). Aethandor 14:09, 3 April 2007 (UTC)Aethandor

Can you put a 1x card in a 4x or 16x slot?

Can you put a 1x card in a 4x or 16x slot? Can you put a 4x card in 16x slot? 12.11.149.5 21:42, 9 May 2007 (UTC)

From the article

A PCIe card will physically fit (and work correctly) in any slot that is at least as large as it is (e.g. an x1 sized card will work in any sized slot)

In other words yes with no change in speed since the card supports only 1x PCIe. Phatom87 16:32, 10 May 2007 (UTC)

Incorrect statement regarding x16 not fitting in an x4 slot

From the article:

It is not possible to place a physically larger PCIe card (e.g. a 16x sized card) into a smaller slot, even though the two would be signal-compatible if it were possible.

This is not true. I have an ASUS A8N-E motherboard. An x16 card will fit and work in the x4 slot. It will just have a quarter of the bandwidth. However, the x16 card will not fit in the x1 slot. I'm sure other motherboards have similar designs. I'm not sure what it should be changed to, but it should be changed.

Also it should be x16 not 16x.

As explained in the introduction a 16 lane card WILL NOT fit in an 4 lane slot but it WILL fit and work in an 16 lane slot that only has 4 lanes connected.

reading that manual that board you link has a non-standard slot with a gap in the back, this means it will work with some larger pci-express cards but missing power pins may pose a problem. Plugwash 20:10, 29 May 2007 (UTC)

PCIe v2 cards in V1 slots, compatibility ?

Do/will v2 cards work in v1 slots ? --Xerces8 15:10, 5 June 2007 (UTC)

Agree with the above

"Overview" and especially "hardware protocol summary" are just terrible. The latter especially looks like it was plagairized from some specification sheet. Anyone else want to just remove it and let it slowly rebuild, hopefully in an understandable manner? 68.39.174.238 09:19, 11 July 2007 (UTC)

I'll put this as simply as possible...

...this page is USELESS. It is probably the best example of penny wise and pound foolish. Is obsesses over minute details of the protocol while failing to explain what the Dickens why those matter or even what the point of most of this is. Look, for instance, at ISA or PCI: Both have technical detail, but with a well-organized system of headings and not so much as to overwhelm the more general information. 68.39.174.238 16:07, 17 July 2007 (UTC)