Computer lag

[Mala]

Just a quick incredibly noobish question:

How come my pc lags when running multiple copies of games (see: 3x FFXI + TF2) when it barely uses 60% of my cpu and 50% of my avail. ram?

I have an 8800gtx too, so i just don't understand the slowdown when resource-wise my system is fine.

[Avanarius]

Directx fails when running multiple apps utilizing it. It's a software issue, not hardware.

[Mala]

Thanks, that makes me