So I'm beginning to think it's something with my power supply but here goes....

I have an Alienware Aurora R1 tower.

I used to have 2 Nvidia Geforce 460s 1GB and whenever I put them in SLI mode, my pc would randomly shut off and reboot during intensive gaming. Sometimes I can game for hours, sometimes 10 mins. The only time I could get the reboot to occur on command was running the Windows 7 Experience Index test; the pc would reboot during the 10 texture load assessment/10 alu assessment.

The only way the pc wouldn't reboot during the WEI test or during intensive gaming was when I would disable SLI mode. The WEI test would finish fine and no reboots at all.

I now have a brand new Geforce GTX 690 and same thing happens when enabling multi GPU mode. Problem is alleviated when disabling Multi GPU mode.

To troubleshoot the issue, my hard drive has been reformatted and a fresh install of windows 7 & the Nvidia driver 306.23 has been done, the pc 9GB memory has been replaced with 16GB dell certified memory. I disabled in SpeedStep and C-State in the bios. The bios has been reflashed to the current version. As you already know, I've replaced my dual 460 graphics cards with the 690. Ran a 10 min OCCT PSU test and was fine.

Again, disabling the SLI/Multi GPU mode alleviates the problem.

What could it be? A failing PSU?

(By the way, the twin Geforce 460s were part of the original Alienware configuration.) They have worked before for awhile in SLI. For the last 6 months, I have been having this issue.

Alienware Aurora R1

Windows 7 Professional 64-bit, Service Pack 1

Intel Core i7 920 @ 2.67GHz 2.67Hz

Bios A11

16GB PC3-10600 DDR3 SDRAM 1333Mhz Dell Certified Memory

Nvidia Geforce 690 4GB