well my whole computer just reboots so i don't think ill catch it in time before it does but ive had my computer on for a extended period of time( 6-8 hours)and it hasnt crashed or gotten abnormally hot from what ive seen its just when i open games
Ok, well if you truly want help, you really have got to help us understand your problem.
1) When did this start happening and did anything on your system change around that time (including any kind of update)?
2) A Complete DxDiag printout would be helpful, you could dump it into pastebin.com and link it here for us
3) Have you recently installed any new software OR hardware?
4) How old is your computer?
5) Have you ever in the past had any similar issues?
6) System specs would also be helpful, you know, processor type, mobo type, ram, vid card, op system, ect.
If your computer is older, the electrolytic fluid inside the capacitors on your motherboard can begin to dry up, causing an array of hardware related issues. This can usually be determined by examining the capacitors on your mobo for bulging.
Personally I always try to eliminate software issues as the cause first before suspecting hardware (unless indicated otherwise by BSOD error codes or in extreme cases POST beep codes)
If it were me, I would completely uninstall all drivers and software relating to your video (Device drivers, manufacturer software, and DirectX ), after removal is complete, do a complete reinstall of drivers and DirectX. If that has no affect, then you most likely have a hardware problem. (Corrupted or poorly coded display drivers are fully capable of causing a system reboot without an error being logged)