I've got a 5970 that has happily been mining away at 800/150 for about 3 weeks now and for some reason the past few days 1 or the other core has been hard locking up.
I've tried lowering the core clocks back to 725 and even down to 500 while leaving the memory at 150, the bloody thing was still hard locking up on me no matter what. I checked power supply as I am running 3 cards on 1kw psu everything seemed ok, even ran a memtest for 24 hours just to be 100% sure.
Out of curiosity I tried bumping the memory clock up to 600mhz and it has been mining happily now for 48 hours at 800/600 albeit loosing 20mhs, but its stable...
Anyone have any ideas why it would do that and if I should be worried that it has caused some kind of damage to my card or the others by leaving them at 150?