any thoughts on how to get 280x's stable with this gpu miner yet?
and why gigabyte 280x's seem to suffer very low hash rate, eg struggle to break 300h/s when compared to an asus 280x that does 360 with ease.
That's what you mean ? Gigabyte like my another rig ?

are they the windforce 280x's rev 1 or 2?
i run 2 of them and one can do 310H/s at 1200/1500 and the other does about 308H/s at 1200/1500. cant seem to push them any higher on mine. even tried different motherboards and the same affect, they are also the ones that drop out 98% of the time....
R9 280x Windforce Rev2. I do it with default clock 1100/1500. Stop OC your CoreClock cuz it will not stable and increase very little hashrate compare with power consumption. I suggest use default for best performance. If you want to OC, just increase a little with MemClock. FORGET TO OC CORE, IT'S NOT GOOD AT ALL.
mine also does not have Hynix GDDR, i have Elpida, which iam assumeing is a much poorer quality brand of memory. i will knock back the OC and list the results.
do you have stock bios, or modded bios btw?
and do yours stay at 99/100% usage or do they bounce around alittle?
Edit.
both cards running at stock clocks with only +20% to power, one does 292 and the other does 288h/s.
very low considering my asus 280x both combined do 730H/s :-/
i use stock bios, no OC, no powertune. My card performance info (stable constant all next info) : Core 1100, Mem 1500, Mem use 99%, fan speed 90%, temp around 55 - 60 ( environment around 30 celsius degree)
I think Claymore build this miner base on ATI 280x factory default parameter, so that if you change or try to change any element parameter of your cards, it will lead to wrong data reply with miner algo. So the result is hashrate drop down or card works unstable.
i believe that its also dependent on the type of memory the card has been build with. as we know Hynix is what 15% faster then Elpida memory which is where iam starting to believe my issue is actually comeing from with low hash rates. weather that is something that can be overcome with fine greater tuneing to the miner itself by claymore or weather it can be adjusted to be stable via memclocks i cant say. how ever OC works well on 280x's and 7 series and even 6 series gpus. my 2 asus 280x's are OCed and are 100% stable for days. my 2 7950's produce 606h/s between them so that 303 H/s per card, and thats under OC, my 6950 modded to 6970 specs does 120h/s with a mild overclock and has also been stable for days. the cards i have listed are hynix/other based memory built in and when compared to my gb 280x's they all OC very well and are stable where the GB dont seem to be very stable even at stock clocks, which as i suggested i believe is due to the cheaper memory type that was used....