I used to get 200-350 fps in CSS

EVGA 8800gts 640mb
SUPER TALENT 2GB 240-Pin DDR2 800
Intel C2D e6700 2.66ghz
320gb Western Digital HDD

Not Software/Virus: Have Reformatted.

Notes:
On PCfan (or the fan/temp prog.) nothing was overheating except my cpu. I checked it and the motherboard's SMART FAN control stopped it during gameplay sometimes. No damage. Checked CPU speed recording programs and still the same speed. Overclocking worked. Turned off SMART FAN and fan always works.
CPU- Stock Cooling... Heard sometimes that might be the root of the problem
Motherboard- Gigabyte. No problems.
I doubt the RAM and HDD are the problems.. Possibly RAM but low chance. No Problems.
HIGHLY DOUBT it's the Vid. Card. No problems.
Changing any video settings: 1280x1024 ALL MAXED->1280x1024 ALL LOW->640x480 ALL LOW = All keep a constant 50-100 fps...
FPS may be high but it still drops to around 40-50 and really choppy.

EDIT: Question: Is it possible for a CPU to be broken, but all the while still function and have a high ghz?

Run memtest on your RAM. Super Talent is decent memory but they are not as renown as Corsair or Kingston.

Ran memtest...Didn't find any errors. Thanks for the advice.

Anyone else have any suggestions or a good PC-hardware diagnostic tool?

Drivers? corrupted file?

Which game or games have low fps? What is your screen resolution? If you're playing Crysis then don't expect your machine to have really good frame rates above 1024X768 on anything above medium.

Well, This is what happened...one day 300 fps...I sleep, the next day 50-100 fps. No software downloads or anything. Uh...I also reformatted so that should have wiped everything clean. And I also updated all my drivers and i doubt there are corrupted files or the Belarc Advisor / Some My Computer Hardware Test would have gotten it.

Crysis: 1280x1024 Maxed out
got 50-60 fps...lol
but thats not what i care about (didn't expect more than that):


Main Game: Counter Strike Source.
More of a mysterious change from high fps to low fps..
used to be 300 then now its 50-100...just a mystery.



BTW: I read another thread that some people exhibit a problem where it just lowers in drop and its the CPU overheating due to stock cooling/thermal paste not thoroughly spread.
I've superfan or pcfan and it doesn't show it overheating. Can this still be a possibility??