I just got my Asus HD 7770 DirectCU a few days ago and have been messing around with overclocking. I never went above 1100/1400 though as I didn't feel the need to push anything. I have had a couple strange instances though. I was beta testing the game Smite and had my screen completely freeze for about 15 seconds on three occasions before correcting itself and continuing the game. That was at 1100/1400. I thought it might have been an OC issue (or simply a beta game issue) and bumped it down to 1075/1300.
At 1075/1300, I had two instances where I had the screen completely freeze on me, like a grey screen with blue and yellow-ish "pinstripes" I guess you could say. One time was playing League of Legends and I could still hear the audio and the other was at the very end of watching a video on full screen VLC media player as it was closing. I have had no instability or screen flickers, BSOD's or anything, just these random freezes that required hard resets.
Finally, I saw some people mentioning that certain mobos have trouble with OC cards or even factory OC cards, so I ran a little experiment using GPU Tweak's monitor function. I set it at 1000/1125 (stock) and 1020/1150 (Asus' tiny factory OC) and got into Anno 2070 and ran it for a bit, then alt-tabbed out and watched the GPU core and mem clocks. The 1000/1125 stock stayed for the most part at 1000/1125 even at the desktop, sometimes spiking down to 300/150 for a second before coming back up. The 1020/1150 on the other hand alternated between 300/150 and 400/1150, never going back to the full clock the way the stock ones did almost the whole time. What in the world is causing this difference? Am I missing something? I caught pictures of the two for comparison. I would post them but unsure how to here.
I would like to keep the little extra performance from OC'ing to 1100/1400-ish at least because even at 1100/1400, I never had temps rise above 51* C with fan at 40%. I'm just a little baffled by the couple random freezes and certainly don't want to damage anything. But having read that the Asus reached 1185/1510 at stock voltages, I doubt freezing at 1075/1300 and about 45* C is an OC instability issue but I'm new to all of this so that's why I'm here.
Finally, my specs:
CPU - Core i5 3570
MB - ASRock H77M
RAM - Vengeance 8GB 1600
Antec VP450 PSU
Win7 Home Premium