Power issue, please help!

Hey guys new to the forums, hello! So basically i built a brand new i5 2500k system with asrock z68 extreme3 gen3 motherboard, corsair tx650w psu, 2x4gb g.skill ddr3 1600, crossfire 6870's, samsung spinpoint 7200rpm hard drive...For some reason I am getting power loss at random...ill just be playing and out of no where my whole system will shut down and boot back up. I yanked everything out so im running on just the basics mb cpu ram and harddrive. I still get power loss. So i took the PSU and plugged her into my old pc and i ran it for a good hour or so and i did not get any power loss...so is it the motherboard or is the PSU possibley bad? I need help here =(

shut down and boot back up.= Sounds like not stable or maybe overheating. Does not sound P/S related at all from this distance.

its not over heating, its not overclocked...i simply just randomly lose power...its gotta be either the motherboard or the psu and im not sure which and i dont have another psu on hand to test it.

Take one video card out and run in single card video mode. Unhook any hard drives etc that are not absolutely necessary. That will lower the power the power supply needs to supply to the board. See if the problem is still there or gone. If gone you need to get a good power supply to test with.

I pulled both video cards and literally have the bare bones in there and its still losing power at random =(, im guessing its defective or the motherboards got issues

ok so its been running stable at idle for like 8 hours now...and once i seem to do anything major it loses power at random still...im running prime95 right now...we'll see if it loses again, but it did last night, im thinking this has to be the power supply....

In addition to the 24-pin PWR connector, do you also have either the 4 or 8-pin PSU connector connected to the AUXPWR plug on the board?

It is the 8 pin connector.

Since you seem to have a NEW rig...I would RMA the board and the power supply. That way you would get both items RMA'd at one time. Instead of RMAing the motherboard to find out it was the power supply and have to wait thru two RMA periods instead of just one. Stuff should still be in warranty with the seller if not over 30 days since purchase.

Good idea, but it seems to be running fine now, but i know theres still a problem some where and im sure its the PSU...if it was an issue with the board i wouldnt be able to run for several hours i wouldnt think? I think when i hit full load or something this PSU is dropping its current?