*BSD News Article 7118


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From: debra@wsinis07.info.win.tue.nl (Paul De Bra)
Newsgroups: comp.unix.bsd
Subject: Re: Weird Problem (50 MHz, SCSI)
Keywords: SCSI, file corruption
Message-ID: <4395@svin09.info.win.tue.nl>
Date: 27 Oct 92 10:57:28 GMT
References: <1992Oct14.220847.22548@sics.se> <168382@mbf.UUCP>
Sender: news@svin09.info.win.tue.nl
Reply-To: debra@info.win.tue.nl
Organization: Eindhoven University of Technology, the Netherlands
Lines: 25

In article <168382@mbf.UUCP> fmt@mbf.UUCP (Mike Trimberger) writes:
>In article <1992Oct14.220847.22548@sics.se> jonas@sisu.se (Jonas Lagerblad) writes:
>>I have had quite a lot of problems with two different 50 Mhz cards, I have 
>>traced the problem to the cache memory, which I don't think behaves quite 
> ...
>>My problems have disappeared totally since disabling the cache, but I have 
>>ordered new faster cache memory, and is eagerly waiting for it to arrive.
>
>We have been evaluating some 50MHz Intel PC systems here and discovered
>that the caches don't work...

I have recently replaced my 386/25 motherboard by a 486/50 and also had
cache and disk problems. There was no apparent problem with MS-DOG but
Unix had trouble booting and kept giving disk errors occasionally.

The cache was *not* at fault (it was a 20ns cache, but with a wait state).
The disk or diskcontroller was not at fault either (worked fine with the 386).

The problem was solved by replacing the *power supply* by a 300 Watt unit.
Even with only the motherboard on a 200Watt ps (and everything else on another)
the disk problems did not go away completely.
A 486-50 mb is a lot more power-critical than other motherboards.

System is running fine now, for a couple of weeks already.
With a 486-50 you must get a very good power supply!