Archived from groups: comp.sys.ibm.pc.hardware.chips (
More info?)
Robert Redelmeier wrote:
> Mark Oueis <markoueis@hotmail.com> wrote:
> > I was wondering if a CPU's performance would degrade over time
> > and use. Would it lose clock speed? Why would it do that?
>
> CPUs don't degrade over time. Generally it works or it
> doesn't. Partial failures are rare. Potentially an Intel
> P4 chip might throttle if the HSF is too small/dirty.
>
> Older MS-Windows machines frequently are slower than when new due
> to bigger registries, increasing disk fragmentation, additional
> process load, etc. But that is an OS maintenance issue.
>
> -- Robert
There are known transistor degradation mechanisms such as gate-oxide
breakdown and hot-electron effects that slowly change transistor
performance. This can slowly degrade timings for signals across chip
and eventually cause the chip to not work. Or it can result in a bit
flip, if it happens in the chip's cache.
Ultimately, the chip will slowly become less *capable*. That is,
instead of a 3.4G chip being able to run at 3650Mhz it will slowly be
able to run at 3600, then 3550, then 3500, etc... The end user
wouldn't notice since the chip is multiplier locked at 3.4G until it is
becomes unable to run at that speed and then it would act unstably.
There are Q&R models that are used to predict failure rates. Chips are
stressed at high temperature and voltage to simulate years of usage.
This is why Intel offers only a 7 year warrantee on their chips.
-Greg
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