I have the same issue with two unlocked MSI 6950's and that same powersupply. I think it has to do with what is related in these two forums:
http://forum.bitcoin.org/index.php?topic=4669.0
and
http://forums.amd.com/forum/messageview.cfm?catid=390&threadid=128404&enterthread=y
Looks like we need to wait for driver updates to resolve the issue. When you do your overclock, make sure GPU-Z is not running. I have found that this and other applications cause the freeze you are describing.
Topic: GPU overclocking relation to hashing power, hanging (Read 1507 times)
Hello everyone.
I was farming with a single XFX 6950 (flashed shaders, 1145mV, 940mhz core/ 625mhz memory ~ 405mh/s) for a while now, and got another one today.
Curiously, when I stuck it in, overclocked it with MSI Afterburner, they make the entire system hang in around 3 minutes. At first its the UI, then the mouse freezes as well.
Now I'm running them both at 1145mV, 920mhz/625mhz at around 390mh/s or at a total of 780mh/s and it seems stable.
Should I up the voltage, or the memory clock, or something for them to be stable at 940mhz core? I am not sure since if it would lack juice it would hang immediately, not after 3-5min of hashing. The temperatures don't go above 75'C.
The power supply is a Corsair TX750 V2 and I'm using GUIMiner.
I was farming with a single XFX 6950 (flashed shaders, 1145mV, 940mhz core/ 625mhz memory ~ 405mh/s) for a while now, and got another one today.
Curiously, when I stuck it in, overclocked it with MSI Afterburner, they make the entire system hang in around 3 minutes. At first its the UI, then the mouse freezes as well.
Now I'm running them both at 1145mV, 920mhz/625mhz at around 390mh/s or at a total of 780mh/s and it seems stable.
Should I up the voltage, or the memory clock, or something for them to be stable at 940mhz core? I am not sure since if it would lack juice it would hang immediately, not after 3-5min of hashing. The temperatures don't go above 75'C.
The power supply is a Corsair TX750 V2 and I'm using GUIMiner.
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