Date: Mon, 23 Nov 1998 17:41:43 -0800 (PST) From: John Polstra <jdp@polstra.com> To: "Jordan K. Hubbard" <jkh@zippy.cdrom.com> Cc: current@FreeBSD.ORG, rom_glsa@ein-hashofet.co.il, Poul-Henning Kamp <phk@critter.freebsd.dk> Subject: Re: Random craches under heavy(?) disk activity Message-ID: <XFMail.981123174143.jdp@polstra.com> In-Reply-To: <44808.911870229@zippy.cdrom.com>
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On 24-Nov-98 Jordan K. Hubbard wrote:
>> I would actually argue that the longer the box has been overclocked
>> the warmer the cpu runs.
>
> I've also had OC'd boxes start failing. A trusty PPro 233 of mine ran
> OC'd for almost 2 years before finally starting to exhibit occasional
> flakiness. I now run it at 200 and it's happy again.
I wouldn't trust it even back at 200. Overclocking causes
overheating, and it's not uniform overheating. Every chip has hot
spots which get much hotter than others. Research has clearly shown
that such localized overheating damages the chips, makes them less
reliable, and shortens their lifetimes.
I used to do a lot of consulting work for a company that built
equipment for diagnosing problems in digital circuit boards. The
goal was to find the bad chip on the board, and the essence of the
process was to somehow inject test patterns that would stimulate the
inputs of individual chips in controlled ways, and then see whether
their outputs matched expectations. We investigated a technique
called overdriving. The idea was that you used high-current drivers
to just blast the test patterns into the chips' inputs, very briefly
overwhelming the outputs of the chips that were driving those inputs.
The hope was that we could keep the duration of the overdriving brief
enough so that the other chips wouldn't be damaged. We abandoned
it eventually. Even the shortest useful periods of overdriving were
enough to reduce the lifetimes of the chips being overdriven.
I believe that similar damage most likely occurs when you overclock a
CPU. It doesn't mean a thing that the package feels cool. There can
still be tiny spots on the chip that are badly overheated.
John
---
John Polstra jdp@polstra.com
John D. Polstra & Co., Inc. Seattle, Washington USA
"Nobody ever went broke underestimating the taste of the American public."
-- H. L. Mencken
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