Sudden Northwood Death Syndrome
The Sudden Northwood Death Syndrome (SNDS) describes the sudden, irreparable defect of the Pentium 4 processor in the eponymous revision "Northwood" as a result of excessive overclocking .
The cause of the effect - electromigration - is a fundamental problem in integrated circuits, but the effect was specifically known in connection with the Northwood core, as this was the first microprocessor for which electromigration was a significant problem. The reasons why the Northwood is more susceptible than its predecessor include the smaller structure width and the higher clock frequencies that can be achieved compared to its predecessors.
The electromigration on which the SNDS is based is mainly caused by 2 effects:
- Increase in core voltage ( V CORE )
- In order to achieve adequate signal quality at increased clock rates, the core voltage is sometimes increased considerably, which leads directly to an increase in the currents occurring (leakage currents and signal currents).
- Clock frequency increase
- The increase in the clock frequency leads to an increase in the current density within the circuit, which leads to increased heating.