Problems with FramesPerSec/Lag while gaming

[Boney]

This just started 2 days ago and nothing I can do seems to fix it. What happenes is while im playing any of my games which is usually CS:S, after about 10-15 mins in my fps start dropping dramatically. If i watch them with cl_showfps 1 or netgraph I will have my normal fps scrolling along and about every half second it will drop to 4ish, then half a second later back up to normal which causes the game to stutter baddly. Other times it just decides to stay at @ 4fps for around 5-10 secs. I have reinstalled my video drivers, defragged with diskeeper, and tried taking the page file off of my raptor hd onto my storage (tried both having windows allocate the space for it and assigning it myself - neither makes a difference). That is about all i can think of that would be the problem, would anyone know anything else?
Thanks for any help anyone gives.

Specs:
Asus K8V SE Deluxe (bios 1007)
AMD 3400+ (754 skt)
ATI 9800 Pro 256mb
1 gig Kingston ram
74gig Raptor / 180gig WD storage hd

 

[mOeeOm]

Try turning on vsync, maybe that will help.

 

[Boney]

VSync made it worse actually - but it is still doing the same thing in general ..... after about 10 mins into the game it gets worse and worse and worse