MSI Big Bang SLI issues

So I put together a new i7 system yesterday, with fresh Win7x64Ultimate, and had no problems. Inside looks like:

MB: MSI Big Bang X-Power
CPU: i7 930 OC'd to 4.1
CPU Cooler: Cooler Master V8
RAM: 6GB A-Data DDR3 Triple Channel @ 1880
GPU: 2 x Gigabyte GTX460s 1GB SLI
HDD: 2 x Kingston SSDNow VPlus+ 64GB RAID0 & 500GB HDD
PSU: ABS Majesty 1100W
Stuffed in an Antec 900 2.

Now, yesterday, after I OC'd it, I of course ran some bench and stress tests to make sure everything was dandy. It was. Ran FurMark for nearly 30 minutes (which I realize isn't all that long, but should bring out any issues) on max settings, Prime95, even the Windows Experience benchmarker thing. Everything was cool. I installed Sims 3, as a hard drive and CPU intensive game to test it out. Worked cool. So what's the problem, you ask? Today, I installed StarCraft II and noticed when I started the game that there was massive tearing in the lower half of the screen. Thinking it was a refresh rate or resolution issue, I set everything to monitor native, 1920x1200 and restarted the game. The tearing only got worse. Now, whenever something is being rendered, it tears, like a wicked bad case of refresh rate mismatch. I quit SC, and noticed that even IE and the nVidia control panel were doing it.

So I shut down the machine, removed the SLI bridge, and replaced it with a new one, and fired it up. Windows had no problem. I disabled SLI and tried hooking the monitor to either card, and they both seemed fine. Enabling SLI seems to progressively make the tearing issue worse the longer it is on. Temps are good, no more than 50C on average for the graphics, 42C for the CPU.

Soo... short story long, does anyone have any ideas? I suspect it is some sort of "these GPU cards Vs. this motherboard" issue, but I hope not. Others don't seem to have a problem, and I could not even find a reference to anyone else having SLI issues, besides DOA and complete failure type; not really blurry and choppy type.

Someone on here's gotta be smarter than I am, think of something I haven't or perhaps even had this problem? They (the MB and GPUs) are popular parts, so there should be plenty of experienced users out there.

Any advice appreciated.

Thanks