There are a few key things to know about the R9 290(X) cards when OCing.
1. Memory clock scales with core voltage. Even Elpida ram can do 1600mhz+(6400mhz effective) at +200mv core voltage.
2. There is a magic ratio for mem clock / core clock that will yield the highest stability if your memory likes the voltage. For me that's 1.36 so 1100core clock * 1.36 = 1496 mem clock if I supply enough voltage(+72mv).
3. These cards will pull a ton of power if you push them. 180W more than stock with 1.35V core voltage. So your PSU is going to give up if both cards are running on 1.35+V and you got both of them at 99% load. (there is reason behind me using a 1200W PSU with only a pair of these cards.)
4. Use Sapphire Trixx to OC since AB is kinda weird with these cards and avoid CCC Overdrive like the plague.
As for the black screens and BSODs. My findings are that if you push the core clock too far the driver recovery will fail and you'll get a nice BSOD telling you. If you puysh memory too high then you will either end up with a colorful repeating psychedelic pattern or a black screen.
Im trying to find out the stock voltage. Im guessing its at 1.25v no?
Idle.
Its a bit weird, if i mouse over GPUz i get higher load VDDC. If i dont its lower??
This is with no mouse over GPUz.
Then when i mouse over.
When i dont mouse over GPUz the voltage ranges from 1.016-1.070 with the average being 1.055.
When i do mouse over GPUz the voltage ranges from 1.047-1.172. This is a big diffrence and i find a bit strange.
Full screen furmark got upto 720w! Ouch. This is stock 290x crossfire.
Futuremark 3DM11 gets to 615w. CPU 3.46 no HT @ 1.1v, memory @ 2133.
Score.
Im finding that even when i try to undervolt to use less power at stock 290x speeds it will bsod with less than -30mv. Is this normal??
Just going to test stability with a few games for a while. I dont think there is any point overclocking too much with 800W PSU.
I do have a 1kw here for when im ready to push the limits. Thats if its going to be enough lol.
Thanks for your OC info btw. I know no two cards are the same so it will probably be diffrent than mine but still gives me a decent guide.
Cheers.