>-----Original Message-----
>From: Aaron Blosser [mailto:[EMAIL PROTECTED]]
>Sent: Tuesday, May 18, 1999 3:52 PM
>To: Mersenne@Base. Com
>Subject: RE: Mersenne: Monitor Flicker on Dell P-II 450 MHz
>
>
>> > Sounds to me more like a "dirty" motherboard or power supply.
>> Chances are
>> > that the computer is emitting a lot of RF at high CPU load
>> whether due to a
>> > "dirty" (ie leaking) motherboard of a bad power supply. So I'd
>> imagine it
>> > doesn't satisfy some FCC Class whatever spec or something.
>I'd have Dell
>> > replace the thing.
>>
>> As the original poster said, he's running on identical 16
>Dell Optiplex
>> systems, they ALL have this problem. This is a highly
>integrated business
>> system with the graphics on the motherboard. There's no
>> indication that the
>> EMI is leaking from the case, indeed, the Optiplex cases that
>> I've seen are
>> very well shielded, with metal braid seals on all joints, etc.
>
>So basically, it's just a poorly designed box. That's what you get for
>buying Dell, but that's just my opinion :-)
>
>If the problem were pervasive in many applications, I'd waste
>no time in
>calling Dell and asking for a fix. As it is, if only FPU
>intensive apps
>cause the problem, they probably wouldn't care.
>
>Possible fixes: If it's a noisy power signal getting to the
>graphics chips,
>too bad. If it's radiated interference, maybe some good
>copper braiding
>around the CPU would help, tied to ground. Or around the graphics
>circuitry. But again, if the problem is interference on the
>wiring, you're
>SOL. Send 'em back and get Compaqs! :-)
>
Actually, I went and looked at the newsgroups and a few people posted about
an apparently bad batch of 1226H monitors, and suggest sending them back and
getting the P-990's instead. So if you have this monitor, perhaps that is
the problem there...
I'm still led to believe that its a bad power supply of a bad batch of caps
that are on the motherboard or something. Having a "highly integrated
business machine" that is "very well shielded" does not mean anything in
this case.
Actually, thinking about it, I'm very inclined to say its a bad power
supply. I'd suggest checking it for fun's sake and seeing how far out of
spec they are. It seems the problem only shows up when the CPU is under a
heavy load, thus drawing more power, and thus drawing the voltage from the
P/S all wacky.
In any case, I'd call Dell and get them to replace the systems or send 'em
back or something. Especially since they are "highly integrated busines s
machines" :)
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