Monitor&sound interference?

[Markie]

Every now and then my monitor displays some faint interference and I can hear interference from my speakers matching with my monitors interference.,It's as if I can see and hear my cpu working when i close pop ups,windows etc.
I have an athlon 500@600 and an sd11 mbo(I know it's not the best!)I also have an external temp sensor and this interference only starts when my cpu gets hot,I am trying various fan cooling setups at the moment to try and stop it happening.any other ideas???
thanx..

[copper]

it could be mobile phones my monitors and speakers go crazy when anyone within 100 yards uses one

[Markie]

No,I don't think it's mobile phones as mine and the misses one's don't cause it.

[copper]

there are 2 frequences (well in the uk there are) that different companies use bt and vodaphone on a lower one and orange and 121 on another it may be that.