Catalyst OC fine, Windows Experience crashes. Why?

Update: After some trial and error I was able to get Windows Experience Index to run at 910/1365. I guess that's the top I should use. The keyboard screen flicker went away at 950/1425.

Still confused as to why the ATI test would succeed and the WEI test would fail?

Now I've picked a 1.5x for the core to the memory, even though I might be able to eek out a bit more speed on one or the other. The theory being a non-even multiple (not that 2:3 is exactly even) doesn't really buy you much. Can anyone confirm or dispute that theory?

The untweaked card pulled down a 7.4 WEI in video. The tweaked settings pull down a 7.4 WEI in video. Seems like a lot of time was just spent accomplishing a negligible effect.

Decided to bump it one more time to 920/1380 and manage a WEI of 7.5. I think I'll stop here while I'm ahead. Still surprised the thing runs at 66C though.

Ran Afterburner and Furmark, 910/1366 was stable for 360s, but started artifacting shortly thereafter at 94c. I tried to make it to 10 minutes, but crashed at 585s@96c.

Everyone says to watch the core temp, but I haven't seen anyone tell me what temp is too high.

Letting the system cool a bit while I do something else. Then I'll try out 900/1350 for another six minutes and see what that does to the temp.

Assuming that's stable, what did I figure out? The max core or the max memory speed? The more I think about it, the more I think stability is more valuable than FPS or WEI.

Obviously o'cing your gpu can cause stability issues.
But so can CCC versions.
What version are you running?
Was the previous version stable?
If it was and you've updated versions recently that may be one of your problems.

You may have a bad overclocker also... There`s no normal core/mem clock as every chip aren`t exactly the same!
Temperature is an instability factor, you lower it, you increase the stability. Thus, you can use higher clock until you reach a stability limit!

Just did a fast google research:
http://www.hardocp.com/article/2009/10/12/amd_ati_radeo...
I think 100C is the max temp for the core... I don`t have a 5770 but I know that my card (5870) can survive at 110-120C so I guess they`re made to support higher temps! I`d say that 90C is safe as they`re running at that temp on that review.

It's a new build with a new card and a new driver, so I can't speak to earlier drivers. The drivers I'm using are up to date, I think. GIGABYTE GV-R577SO-1GD, Windows 7 64-bit. CCC 2010.0302.2233.40412, which I thought was AKA 10.9. Drivers are 8.762.0.0 8/3/2010.

With Furmark 10.7 (I couldn't get 10.82 to work) I was able to push the GPU to 94C at 1920x1200 for 400s at 890/1335. Stability is compromised above that, at least once the GPU gets hot.

Just turned on it's sitting at 49C and I could probably abuse it for a few minutes before melting the case. Now I have no external heat in my mancave, so perhaps a fast GPU is my best option to keep warm this winter, but I was looking for something more romantic like a gas fireplace, but don't tell my wife.

Update: Just finished Furmark at 920/1380 (which it booted to) for 600 seconds at 1920x1200 with no problems. Final GPU 89C. I guess I'll keep it here until a game crashes on me, then I'll back it down some. I must have pushed too hard last night and it took some down time to recover.

Furmark 10.7 is returning an average of 42fps. The best test I had was 44fps, but that crashed at 585s. Close, but I'd prefer a system that doesn't crash.

Just for fun I ran Furmark against my old PCI/AGP based system (2GPU) and it clocked 2-3fps on PCI 1024x768. That was out of an overclocked GeForce 6200. The AGP was a Radeon 9600, but that didn't seem to want to let Afterburner play with the settings. No big, I've moved on.

In conclusion, I have a system that isn't quite as fast as Cjavascript:%20validform(this);CC says is safe, but I have a stable system and I'm happy.

Best answer selected by toscrawford.