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Old 2002-10-25, 01:37   #1
Aug 2002

118 Posts
Default Prime95 and the earphone jack

I noticed something very wierd. When I am running Prime95, I can hear a wierd siren-like interference sound coming from my earphones when they are plugged into the earphone jack on the front of my computer. Whats even more wierd, is that when i plug my headphones into the jack located on the side of my monitor, it doesn't make that sound.

At first I thought 100% CPU useage was causing the siren sound, but running Folding@home does not make the sound, even though it runs at 100%. Does anybody know what causes this?
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Old 2002-10-25, 07:01   #2
Deamiter's Avatar
Sep 2002

11710 Posts

Sounds to me like the 100% CPU usage IS causing the noise. My guess is that some AC 'noise' is leaking into the sound card (or wherever the jack is). Actually, my first reaction is that the noise is caused by a 'droopy'power supply. Make sure your PSU can handle the load you're asking it to. If not, it could be sagging just low enough to cause some chips to malfunction. Actually that's happened to me before... I got a weird AC coming from a chip that wasn't powered quite properly. Anyway, the Folding@home wouldn't affect it because it's maxing out the CPU in a different spot perhaps?

Anyway, there's probably a better explination, but you might look at the voltages on your PSU wires to make sure they're not sagging too much.
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Old 2002-10-25, 20:59   #3
smh's Avatar
Oct 2002

29×41 Posts

Can't remember what exactely causes that sound, but there are some fairly lengthy discussions in the mersenne mailing list archives from a couple of years back (maybe as far as 1997 )
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Old 2002-10-30, 00:19   #4
crash893's Avatar
Sep 2002

23·37 Posts

I get that with even my speakers

i was going to make some sort of sheild for the emf interfearnce
( cardboard covered with aluminum foil then covered with tape ( so it doesnt bridge anything ) then ground it to the case or soemthing else)

i havent gotten to it yet but ill tell you all how it goes
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