Cranking the GPU clock to 1100(+10%) gets me about 660 Mh/s(+10%), but anytime I try to underclock the GPU RAM, the system hard locks upon startup of cgminer. It does this with v2.10.2 & v3.1.0.
When using --gpu commands/arguments in cgminer.bat, should one
enable or
disable Graphics OverDrive in the AMD Catalyst Control Center?
PRO TIP: Some cards have these stupid aluminum trim disks stuck to the center of the fans. They look nice, but REMOVE THEM BEFORE INSTALLING THE CARD. One of mine came loose and got stuck in the fan/shroud, stopping that fan entirely. I only discovered it after noticing my GPU temp was at 96°C!
I shut down the system, dislodged it, then removed the other one (which was intact) so that it could not repeat the problem in future. Had it been a single-fan card, it could have really overheated in a very short time, possibly killing the card/starting a fire/ending the world.