Computer suddenly slows down after 20-30 mins

[kebber]

For regular usage my computer is fine.  But if I want to play games or watch videos it seems to be much slower.  I have been getting much lower frame rates on my games and the audio on the videos aren't in sync with all the action.  After each reboot everything would be just fine but 20-30 mins later it starts to slow down again.  I've had my computer for 2 years now.  Last month I installed a new video card and a new hard drive.  I thought it was the video card so i replaced it with the old one.  Then I just didn't want to deal with it anymore and decided to format the whole thing and the problem still exists.

Anyone have any idea what the problem could be?

[Carbon Dudeoxide]

How much RAM do you have? Have you had this problem before?
Do you think overheating may be the issue here?

Also, what Operating System?

[kebber]

I have 1.5gb ddr1 ram

xp svp2

and no this has never happened before. when i play counterstrike source i usually get around 25-50 frames per second
but when the comp slows down 20-30 mins after reboot i get like 6 - 12.

[jerryheavyarms]

I think this is overheating.. ALthough you said you changed your videocard..Have you cleaned your computer when you installed your videocard?

Try doing this..
Open your computer case and put a fan next to it and see what happens..

ALso you can dload speedfan to monitor your temps.

[!~*:.Pink Floyd.:*~!]

yes but why would it just start doing this?

[!~*:.Pink Floyd.:*~!]

try defragging

[kebber]

I think this is overheating.. ALthough you said you changed your videocard..Have you cleaned your computer when you installed your videocard?

Try doing this..
Open your computer case and put a fan next to it and see what happens..

ALso you can dload speedfan to monitor your temps.

okay.. ill try that

[kebber]

try defragging

defrag a computer I just formatted?

[kebber]

even with the fan i still get the same problem.. and im using speedfan and the temps seem to be fine.

[Carbon Dudeoxide]

What are the temps?

[kebber]

GPU 45C
system 33C
cpu 40C
AUX 36C
HD0 31C
HD1 35C
Temp1 37C

[Broni]

What is power supply wattage?

[stevejohnson1958]

Is it possible some other program may be running in the background...taking away from the game's performance?  Like a scan...or some other task?

[kebber]

450W

Is it possible some other program may be running in the background...taking away from the game's performance?  Like a scan...or some other task?

I just formatted it 2 days ago only drivers and steam installed
I have been using this computer for 2 years.

[Broni]

What are those temps, you posted?
Idle?
What are temps when computer slows down?
What processor?