Gigabyte 280x with elpida onboard is giving me stable 13.5 sols. I did nothing besides unpacking and launching the miner ))
I have no idea how you managed to get 13.5sols. The most I could get was 11.50 with some heavy overclocking.
Just use ancient drivers, I am still on 13.12 with my Tahities and feeling good

I have tested the shittiest card with lowest ASIC quality and the slowest hashrate on ALL algos. Got the results on 1050/1500@1.094v btw