I am House

[Katoke]

GFX card too close to sound card? Does it only happen when watching HD videos or something?

[Norellicus]

If you can still get sound when playing these games from a set of external speakers like you could with the videos, then I would venture to say that the entirety of your problem lies with the internal wiring to your built-in speakers overheating due to other components receiving high load and putting out excess heat.