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- Xref: sparky sci.electronics:18350 misc.forsale.computers.pc-clone:599 misc.forsale.computers.d:273
- Path: sparky!uunet!ogicse!news.u.washington.edu!stein.u.washington.edu!bketcham
- From: bketcham@stein.u.washington.edu (Benjamin Ketcham)
- Newsgroups: sci.electronics,misc.forsale.computers.pc-clone,misc.forsale.computers.d
- Subject: Re: 486 CPU KOOLERS FOR SALE
- Message-ID: <1992Nov5.083110.7351@u.washington.edu>
- Date: 5 Nov 92 08:31:10 GMT
- Article-I.D.: u.1992Nov5.083110.7351
- References: <1992Nov4.084645.16364@brtph560.bnr.ca> <1992Nov05.024950.15606@kksys.com> <Bx8CA2.GF2@ns1.nodak.edu>
- Sender: news@u.washington.edu (USENET News System)
- Organization: University of Washington, Seattle
- Lines: 56
-
- Well, I can't say I've done any tests on CPU lifetime vs. heat, but that
- doesn't seem to have stopped many of the others who have posted in
- regards to this CPU fan thread, so why should it stop me?
-
- Everyone seems to agree that lower temperatures are in general better
- for semiconductors. However, the question seems to be, does the decrease
- in CPU temp that these fans achieve really make any real difference? I
- find it hard to believe that it does. I have actually *never* seen a
- CPU fail in my relatively small personal sample of systems...
-
- CPUs just aren't the weak link in a computer system. The
- things that will fail will be the disk drives, connectors and sockets,
- switching power supplies, monitors, and keyboards. Statistically, as
- memory gets denser and larger, the chances of radiation hits causing soft
- errors will start to become a bigger problem for personal computers, as
- it already is for larger systems. But CPU failures?
-
- My guess is that
- 90% of the small number of CPUs that ever do fail do so due to power
- spikes, esd, transients from the bus or the failure of other chips, or
- (probably the biggest factor), incorrect installation by unqualified
- users.
-
- Semiconductors are rated to operate normally at temperatures that
- subjectively feel "too hot" to the touch (85 C) without any compromise
- of reliability. If these 486s are really exceeding 85 C, then maybe
- these fans are needed, but I really doubt it. (Yes, I have a source
- for this 85 C number, albeit a questionable one I'll admit: the 1986
- Intel 80386 data sheet. (That's case temperature, not ambient or
- junction temperature.) So maybe, just maybe, the 486 is rated for a
- lower operating temperature, but I really doubt that, too.)
-
- Plus, nobody has considered the possibility that these fans might do
- more harm than good. For one thing, as any service technician would
- agree, I'm sure, the biggest problem impacting system reliability is
- often the users opening the box up. The chances of slipping with a
- screwdriver and doing major damage are probably orders of magnitude
- higher than the chances of a CPU failing within even 10 years. What
- about the vibrations and electrical transients introduced by these
- fans? Were any studies done about these factors? After all, they are
- bonded right on top of the CPUs. I would imagine that the CPU sockets
- are probably a good bit more susceptible to failure or intermittent
- noise problems, exacerbated by vibration, than the CPU itself.
-
- So for those few critical applications where even miniscule chances
- of failure are a big problem, just replace the commercial-grade 486
- with a mil-spec temperature range one, and forget about heat problems.
- And the rest of us can forget about them too, I'll wager. If someone
- wants to do something that has a real impact on computer reliability,
- develop mass storage devices without moving parts, and work on better
- error detection and correction for RAMs. The only good reason I have
- heard of for cooling a CPU (with a Peltier device, in this case) is
- to run it twice as fast as it could run at normal operating temperature.
- Temperature-induced failures? I don't think so.
-
- --ben
-