BSOD's while Overclocking - Help please

Sup guys, I have a FW-550 F/B (specs here: http://www.productwiki.com/sony-vaio-fw-series-vgn-fw550f-b/). I want to overclock it to 600/800. After using Riva Tuner to set the clocks, I always run a FurMark stability test (1280x1024, 4xAA), while monitoring the temps with GPU-Z. It always crashes to a black screen (the monitor doesn't turn off, I just stop hearing anything and later I get a loud buzzing noise). The only solution is to do a hard reboot.
- It's not a temp. problem, sometimes it crashes at 60C, sometimes at 70C
- The GPU is not faulty, at normal clocks I beat Far Cry 2, Dead Space, RE5, Crysis, and Fallout 3 at pretty high settings without a single crash. All those games push the GPU load to 100% and temps go up to nearly 70C.

Some interesting things
- I had this problem in Mass Effect at normal clocks. I lowered the settings until it was almost pixelated but it persisted. I did some research and it seems i wasn't the only one, so I stopped playing the game until I could find a solution
- After this problem, I checked the Event Viewer. Apparently, they're all bluescreens. The description says "Display is not active'", with the source being "atikmdag.sys "

Maybe it's a driver issue?

 

At higher overclocks, you will encounter driver instability. That's what your black screen is. You're driver stack is crashing because you're pushing your card too hard. Try a more mild overclock, like maybe 10mhz at a time, and then stress test it. You can also try updating your drivers and see if you can maybe get a little bit more of an overclock.

 

Okay, I got it. Apparently it was a driver problem. I used Mobility Modder to update my driver to Catalyst 9.11 and bam! no more crashes. So if anyone has my same problem you know what to do. Thanks man.