Im running a self built computer and it has never worked correctly. after running a big application it restarts over and over until i turn it off and let it sit for a few hours. ive taken it to professionals and they cant fux the problem they just get it running for a few weeks then the restarting begins again ive replaced the power supply and motherboard and its still having problems please help.

What application are you running when the restarts occur?
What is your Operating System (98, XP Home, XP Pro, ....)?
How much RAM do you have?

The more information you can provide, the better the chances of finding a solution to your problem.

Sorry =/ i have windows xp with 512 MB of ram
it usually happens after playing counterstrike for a long time. or if i leave the computer on for a long time and then try to play the game. or the other day i played cs and then tried installing a driver and it restarted. the time in between the restarts gets shorter and shorter until it wont turn on at all and i have to get it reformatted. To get it reformatted the place i took it had to take it apart and use their parts to get it to turn on? thats what they said but once its reformatted it works..for a while any ideas?

Sounds like a cooling problem to me:

Download the system analysis program 'Everest' so you can get detailed information about your system:
Everest download
Temperatures, voltages and fan speeds are shown under Computer>Sensor.

Load up some programs, play the game then (before it crashes) take a look at the temps from time to time. Let us know what you find.

Yea rimmer sounds right, GO RED DWRAF!

Also, do u play any other games apart from CS? It could be a heating problem, or a video card problem, i had a problem like this with UT2004, and i just needed to update my video card driver and directX, It usally happened to me as soon as i started playing, but it could still be the same problem, make sure all ur drivers are fully updated. Also make sure CS is fully patched.

Also does it restart during other heavily disk activities eg. running an antivirus or spyware scan?

ok i downloaded the everlast home edition with nothing running the temp is 50C for the motherboard; 43C for CPU; 36C for IBM. When running the game it goes up to 55C for motherboard; 52C for cpu and 36C for IBM. I dont know if that is too hot or not.
And yes it does restart at other times. It restarted when i tried to upload drivers off the cd for my motherboard.
And my video card is a NVIDIA GeForce 4MX 440 With AGP8X.

well the problem really does sound like heat, but the results u show take that possibility out.................

The CPU and IBM (hard drive?) temps sound fine but the motherboard is hotter than the CPU? That makes no sense. Are those all the sensor readings you get? What's the make and model of the motherboard?

What is the state of your graphics card (what is it?) does it have a fan and is it running? What about the fan in the power supply? What is the wattage rating of the power supply?

If the sensor readings are right I still think something is cooking in there.

I used that everlast home edition and found that my heat readings were completly different from ones given to my from the BIOS and from MBM
Once again i recomend getting MBM for best readings. ( you need to no your MB type )
http://mbm.livewiredev.com/