-----Original Message-----
From: Joe Decker [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, May 18, 1999 10:09 AM
To: Curtis Cooper
Cc: [EMAIL PROTECTED]
Subject: Re: Mersenne: Monitor Flicker on Dell P-II 450 MHz
Curtis Cooper wrote:
> Has anyone noticed monitor flicker on a Dell OptiPlex GX1p
> P-II 450 MHz? We have installed ntprime on 16 of these
> computers and noticed the monitor flicker on each one.
> We know that the video chip is integrated on the motherboard
> so we cannot move the video card to a different slot away
> from the CPU, as has been suggested when this problem has
> come up in the past. The refresh rate for the monitor was set
> at the maximum value of 85 MHz.
>
> Is there a solution to this monitor flicker problem?
Not easily. This precise model is common where I work right
now, and I'm running prime95 on 3 such machines. In every case
the problem is quite visible.
In one case (not a personal workstation), I just left it on,
in another, we put in a separate monitor card and that worked
around the problem (needed a particular video card in that
machine anyway), in a third, I worked with the user of
that machine and set up prime95 not to run during the hours
she was likely to be working.
The problem is not only prime95, although it is far more
pronounced with that than any other program I tried. For
example, writing a small infinite loop in JavaScript and
running that under Netscape causes similar but more minor
interference.
Having a faster refresh rate doesn't help. The effect is
still undiminished at 120 MHz. monitor refresh rate.
I did call Dell for a workaround, and tried a number of
things they suggested, but it looks to me that the processor
is directly affecting the video signal (by either modulating
the power supply or, more likely, via induction through some
unintentional antenna on the PC board.)
--Joe
________________________________________________________________
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.
I suppose you could test the theory out by tuning a radio to some station
and seeing how close you can get to the computer without it messing with
your reception. (just kidding)
Good luck.
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