ok so last night i was playing css and about every 5 seconds or so my fps would drop form like 400 to exactly 45 fps. does any one know what my problem is?

Maybe network lag on a weekend.

naww it is still happening. can it be that my gpu is getting too hot?

Without any details of what your computer is made up of, how fast it normally runs, and what the temps of everything is, all we can do is guess.
 
I'm going to go with the hamster in your computer has a broken leg, you need to get a new hamster.  (that or aliens, but hamster is more likely.)  If you'd care to provide us with any details however, I'd be glad to change my mind.

Im going with the aliens, as they like to see hamsters suffer, and usually steal their food. So its underpowered , low powered hamstwerization

Is it even a problem?  im screaming if i hit 45 FPS in just about anything.

From 400?! Thats going from ultra fast to ultra slow, it is like driving a car at 90 mph, then going down to fifty, you'll notice it, fast!

No, it's like going from 90mph to about 10mph
 
@rolli59: Network lag doesn't decrease framerate.
 
@homeboy: Does it drop to 45fps and shoot straight back up, or stick at 45 for a bit?

yeah it goes from 45 to 400 to 45 and it kept going. i fixed the problem though. i guess it was getting too hot. cuz all i did was take out my gpu and take off the fan and put some new heatsink on it and it was fine. back up to my regular 400 fps. getting my water cooling system tomorrow ill see if it makes a difference or not.

Watercooling an 8600GT? Seems like a waste to me.

not just my gpu. my cpu my chipset motherboard and the gpu. got great results overclocking is incredible while keeping the temps lowwww