Why does my PC Crash? (Sorry for Generic Title)

[AndrewDoK]

I am not a novice nor an expert PC user but I like to think I know a decent amount about my hardware and software. My problem is my computer crashes about every 45minutes while doing pretty much anything (from games to web browsing).

By crashing I mean it just locks up, I can still see what I was working on or watching but it is frozen in place.. I do not however get a blue screen or any kind of instant-restart.

I've attempted multiple things to try to fix this:

• New 850w Power Supply
• New Video Card
• New Heatsink
• Lowered RAM Voltage
• Completely Formatted PC and Reinstalled from Scratch
• Completed All Windows Updates & Video/Chipset Driver Updates
• Checked Temperatures my GPU and CPU are running at (all are within acceptable ranges)

None of these have even slowed down the crashing, it tends to happen more quickly while using graphics intensive applications (or even just youtube videos).

If Anyone has any suggestions please let me know, any advice is greatly appreciated. If you need any more information I will get any info I can. Thank you very much in advance.

Below are my system specs:
Processor: Intel Core2 Quad Q8200
Mobo:nForce 630i
Video Card: Nvidia GEForce 9600 GT
OS: Windows 7 Ultimate (Fully Updated)
Sound: Onboard Realtek HD
HD: 2x 500gb SATA drives in Mirror Array
Power Supply: 850w (brand new, upgraded from 600w trying to fix)

[Enriqueta]

There can be some incompatible hardware of software. When your system crash then do you get a blue screen. If yes then there is a error message on the screen. Note down that and look for solution. Second thing for software fault you can use HijackThis. This is a free easy to use tool for checking the number of all processes running in your system.

[chris12345]

There are some virus and threads which cause the problem of crashing the PC.You must need to install anti virus which protect your PC from these activities.

[maria.sizer]

There is a virus in your system, due to this your PC has been crashed.
If Blue screen appears then there are the following reasons:
The Windows paging file is less in size than the memory
There is a STOP error that is causing the system to stop.

If you don't find any solution then You should use a third-party Stellar Windows data recovery software to recover files

[AndrewDoK]

Thanks for the help guys but a virus definitely isn't the problem. I know this because I have completely formatted my hard drive twice.. any virus I had would have been wiped out then. My problems persist even right after a clean install. I'm pretty sure it is hardware related as I've tried many different versions of windows (from XP to 7 both 32 and 64 bit versions) and a plethora of driver versions. The strange thing is all hardware monitors show my temperatures within normal levels.
Thanks for the help guys.

[Dr. V]

Remove some of the memory modules installed on the computer. This can be issue related to hardware or software. Sometime due to bad sector in hard drive such thing happens. You can also analyze the blue screen error log file in Windows to get the exact cause of crash. If you face a blue screen then there is a error code mentioned on the screen. That is the best to find the cause for the same.