"Dave Platt" wrote in message
...
In article djt_d.14823$Fy.7702@okepread04,

snip

I suspect that the QRM you are hearing is from the fundamental or
harmonic of one of these switching-regulator oscillator rates.
Heating and cooling of the CPU and motherboard are probably causing
the switching oscillator to drift a bit.

As to how to get rid of it... you're already on the right track, I
think... shielding and filtering. Make sure that your monitor and
power (and other) cables have ferrites on them, as close as possible
to the PC case. Make sure you've got a "tight" PC chassis, with metal
shielding in every possible location (including screw-secured plates
over any unused PCI slots, snap-in metal shields for any unused
hard-drive bays, etc.). I recommend a chassis which is actually all
metal, rather than one of the new lighter-weight plastic chassis with
an anti-EMI coating on the inside. Don't run your PC with the side
panels off - put 'em on and fasten the screws.

As for the gamer-style transparent acrylic PC chassis, forget 'em - I
have serious doubts as to whether a PC build in one of these can pass
the FCC Part 15 tests, let alone be RF-clean enough to use in a ham
shack.

--
Dave Platt

I've already buttoned up the all metal case with grounded side covers.
I even made sure (with a DVM) they were grounded. (The ends of the
mini tower are metal with the front having a plastic facia on top of the
metal case front).

No help. The only thing that helped was taking both covers off and
blowing air through the chassis. I monitor 3 temps - CPU, Motherboard
and power supply exhaust air. Before the box fan, I was running CPU
at 129-140, Motherboard at 100-118 and power supply exhaust at
room temp +16 degrees (F).

Now I've got CPU at 113, MB at 93 and exhaust at room + 8 deg.

I was planning on buying a can of air and further investigating this but
I feel I've solved it with the box fan. The interference is gone and my
PC is cooler.

Thanks for the ideas!
--
73's es gd dx de Ken KGØWX
Grid EM17ip, Flying Pigs #1055,
List Owner, Yahoo! E-groups:
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