I just built a core i7 rig about a month ago, and it has a very annoying problem, the PC will freeze for about 1-3 seconds randomly, and I have no idea when it is going to happen. It usually occurs while gaming, but it also has happened when I am just navigating through windows explorer or am working in Microsoft Office. I ran several virus/spyware tests all which came back negative, have flashed the BIOS to the latest version, have reformatted the hard drive, tried installing XP and Windows 7, instead of Vista but the issue still persists (on ALL of these OS-es). I have also run a Drive Fitness Test on all drives, and have tested the memory by swapping the RAM modules with a set from another computer. every test I have run is indicating that my hardware is fine, and I have tried reformatting and running different Operating Systems so it is not a software issue. I think it may be the board because it does strange things while POSTing sometimes like disabling my LAN ports completely when I did not touch the CMOS settings for onboard LAN, and once when restarting my computer it just did not POST at all and took me to a black screen, and did not beep at all. but I just don't know, and being an IT major in my school, I have learned that if it isn't anything else it is either the Power Supply, or the Motherboard.

My Specs:
CPU: Intel Core i7 920 w/ stock fan
Mobo: Gigabyte GA-EX58-UD5
RAM: 6GB G-Skill Triple Channel DDR3 1333 CAS 7
Graphics: Powercolor Radeon HD4830
PSU: Thermaltake 850W 3 +12v rails at 18A
Primary HD: Western Digital Caviar Black 640GB
Primary OS: Windows Vista Business 64-Bit
Secondary OS: Windows 7 Beta 64-Bit, Windows XP Pro w/ SP3

Yeah sounds like PSU or Motherboard.

Is the CPU overheating? whats the temp?

Temps are good, New RealTemp reports CPU temps on all cores at about 35-40 C, doesnt go over 65C when running an instance of Prime95

35-40 is average but 65 is bad. Really under load you want 40-55.

dont think its whats causing your problem though. Try memtest86 on your ram. And what are the specs of your PSU?

PSU: Thermaltake 850W 3 +12v rails at 18A

I had a bad power supply in this rig before, what are the odds of 2 bad power supplies in a row?? another thing making my wonder is I tried testing the other bad PSU with a voltmeter, and while doing so, it sent a hefty electrical charge which turned my computer off, could this have damaged the motherboard, or did the safety mechanism on the PSU catch it (note I did this with all other peripherals disconnected, there was no RAM or Videocard connected but I probably should have disconnected the PSU from the motherboard)

It could possibly have damaged the motherboard, im not sure. Had a bad PSU once and it killed everything attached to the pc. If so it may expalin your POSt errors etc..

any chance it would have damaged the CPU? or is that not likely. would think if the CPU was shot it wouldn't boot at all...

unlikely, sounds like maybe the motherboard

Just found out today it was the motherboard. turned the computer on, and got a screen that says MAIN BIOS CORRUPTED. This will be the last time I ever buy a Gigabyte motherboard, it only lasted me about 2 months, at least it has the DUALBios though, so even though my Main BIOS is fried, I can still boot into windows... cant change ANY of the settings though, so I am stuck running with my memory underclocked and with the wrong timings... ordered a DFI board and am going to replace it in a few days. thank you jbennet for all your help