Monitors lose signal/ system crash during gaming.

Hello,

I really hope someone can help me here. I built a rig around 7 months ago and every so often (sometimes 1 week later up to even 1-2 months later) my monitors will lose signal, sound will loop for a few seconds and I am forced to physically restart. This has only happened during gaming. I have looked up the event viewer only to find the only issue after an episode was the forced restart. One monitor is using an HDMI and the other a DVI. My mobo, HD and fans seem to be functional but its as if no one is home.

System drivers are up to date. During load cpu is around 40c to 50c and gpu is around the same sometimes up to 60c. I have tested the ram with HCI Memtest for a few hours. I have tested the GPU with FurMark using a burn-in test. HD is fine and all of my mobo LEDs are blue (which I am sure means no errors).

As a side note, I use a lot of resource intense programs such as Zbrush, Maya, etc and have never had this problem arise.

Please if anyone can solve this I will name my first born after you. . . . .. . . Ok not really but I will be VERY grateful lol.

My hardware is:

Windows 7 Home Premium
MSI 990FX mobo
ATI Radeon 7870 card
AMD FX 4100 CPU
8 gigs of Gskill sniper RAM
Corsair TX 650 PSU
1 TB Seagate HD
Battery backup is a APC 550VA 330 WAT

Any ideas on what the problem may be?