So this is my third build or so and my first time I've attempted to do any actual overclocking. I've got some of the basics down. I can't seem to get past the issue of 3dmark (including vantage) crashing when I apply any OCing setting to my vid card.

I made several successful OCing runs of 3Dmark11 a few weeks ago. Then it just stopped working. If I apply even the most mundane OC setting, it crashes. It either crashed towards the end of the loading process for the primary graphics test, or in the first 5 seconds of the run.

I'm running the following:
I7 920 OCed to 3.8
2 X Asus 580 GTX (in sli, currently stock setting)
64-bit W7 Pro
9 gigs of patriot DDR3 @ 3040/760mhz
1000w PSU
aftermarket cooling for both cards and cpu.

I've got the most recent drivers for everything. During the first week or so after building this machine I was having huge "video driver" problems, crashes, random reboots, etc etc. It's stable now except under the conditions of any benchmark tests I run. I'm using Asus Smart doctor to OC my cards and MSI afterburner to monitor speeds/temps.

The only changes I've made since then was I bumped the CPU up slightly higher than I had originally intended. Is this perhaps why I'm unable to run any benchmarks? I'm pretty sure it's not a PSU issue. I ran a MEMtest and it came back with 0 errors. I'm really confused. I was able to hit 941 (782 stock) core clock 2449 (2004 stock) mem clock on my 580s on stock voltage, now I can't even bump it up to 800 core without a lockup. I've tried raising the voltage and doing different combinations of OCing and nothing seems to work. I also can't complete a full burn-in test on furmark without a reboot happening at some point but that's another story.

Was there a silent patch I missed, or perhaps the new CPU clocks aren't co-operating with the cards. I'm obviously no computer pro, any help would be greatly appreciated.

Thanks.