> >Either way...EMF from the CPU definitely appears to be the culprit. One
> >possibility which I emailed the original person was to place some braided
> >copper between the CPU and video card, and tie that to a good ground.
> >That's not practical though. :-) We don't all have copper braiding lying
> >around.
>
> What would that do, effectively shield the video card with a Faraday cage?
> Anyways it looks like the EMF may be from the FPU. I'm sure there are
more elegant solutions, but that one would be pretty cheap.
Essentially. A grounded copper mesh is pretty good at picking up
multifrequencies, and since it's grounded, the signals tend to dissipate.
> >Remember those old hobby computers from back in the 70's that
> generated so
> >much EMF you could make a TV flicker from the other side of your
> house? Or
> >how you could place a radio nearby and run a program that
> generated so much
> >noise in such a way that you could actually try to play a tune? Oh, for
> >fun... (Okay, I'm not quite old enough to have used a hobby computer in
> >the 70's...but close, so close).
>
> I bet the FCC had a lot off about that...which is probably why modern
> computers come in a stainless steel box that's grounded through the 3rd
> wire on the power connection.
I don't know how upset they were back then. In those days they were
probably more lax as long as you weren't interfering with other peoples
stuff.
These days, the FCC has stricter guidelines, requiring a class B for any
prebuilt systems. Oddly, you can still build your own computer from parts
and not have to get it certified. For businesses, you need class A whether
its prebuilt or homebrew.
I will say though that for most computer parts nowadays, you can slap one
together yourself and it all fits together much better. Motherboards have a
lower power consumption, monitors are EMF shielded, and cases are either
heavy duty metal or lined plastic affairs. The ATX spec for motherboards
and cases actually contain language for EMF radiation, and there's a nice
metal thing that comes with an ATX case to fit around the ports that stick
out the back, limiting the radiation leakage there.
Good stuff.
The big problem is radiation inside the case. For the longest time, sound
cards would either pick up alot of stray noise, or generate a lot of stray
noise themselves. Then they got better when they started packing more stuff
onto one chip, avoiding all that noisy glue logic.
CPU's use less power and generate less noise/heat, but I still consider it
VERY unwise to put something like a graphics chip withing 2cm of the CPU.
You're just *asking* for trouble there. :-)
Aaron
