[Solved] Overclocking Twin Frozr iii 6950

Hello, ive been trying to get this gpu stable for some time now. I can get it up to 900mhz and it will run sometimes a while sometimes not. I've been using crysis 2 as a benchmark because kombuster and unigine benches work but crysis 2 will eventually stop working and same goes for metro. While BF3 will work fine. My main question is it either one of these things.

1)Overvoltage? Heard to much can make it unstable.

2)Undervoltage? Certain games like metro and crysis 2 are quite taxing and power hungry so i could need more.

3)Just can't do it? I've heard some gpu's can't get past 900mhz.

I just find this frustrating because this cards advertised as a great overclocker and i cant break past this barrier.

Btw im in crossfire with these two cards maybe another problem? But i feel like I've nailed it down to one of those 3. I'm also using the latest afterburner beta because regular afterburner wont let me mess with voltages cause its not supported with my card yet but the beta is. Also I haven't unlocked it nor do I want to, just a faster clock speed.

I would greatly appreciate some insight from someone on this because i dont wanna kill my cards. Just had this thing about 3 months I'd like to have it longer than that. lol Thanks everybody!

Btw I have plenty good cooling my cpu is overclocked but thats been stable for almost 2 months now. Also i disabled ulps in my registry.

Basic specs-i7 2600k oc to 4.2ghz cooled with an h60, PNY 8gb 1366mhz ram using XMP, twfr 3 6950 oc edition cfx, WD caviar black 1tb, asus sabertooth p67 and a 1200w coolermaster silent gold PSU

Forgot to mention this but I've had these things at 880 and no problems for the whole time of having these cards I'm just curious if its that fine tuned that a specific voltage will work with it or my gpu cant do it. Thats what's getting to me now because all the 6900 series gpus are all the same cayman model and ive read people with ridiculous 1ghz speeds with this specific model card. I just feel like I'm missing something here or did i just get unlucky with these cards?

Your probably right. That's what i was thinking the most. The only other thing i can think of is that I'm using amd beta drivers now and i was also using afterburner beta. I figured could have something to do with that but i just uninstalled afterburner. I'm just gonna wait till its actually ready. Plus I don't wanna kill my cards or always worry about crashing. I'd rather just know it work lol.