This is without specific optimizations for the tahiti chip compared to hawaii and with the standard djm34 miner (not my own).
Will update the OP soon.
Whoever donated and wants the tahiti bin just ask me.
Hmm.. I have 1140Kh/s with the original public Lyra2RE kernel.. This is with 280x running at 1130/1570, though.
Or is there some "hashrate halving" happened again, I haven't been following too closely.
I didn't try a clock so high yet, the cards aren't mine so I must be careful :-)
It must be tuned for Tahitii and I must try it with my miner which will probably provide another little boost.
People are reporting much different hashrates for the same cards.
It depends on driver version (for the standard kernel), but also on memory latency (for both kernels).
I believe cards with Hynix ram have at least 8% advantage over Elpida ones. I don't know which type of ram the 280x I'm using do have.
I just tried with 835/1500 and 1000/1500, with the public kernel.. Compiled on 14.6.
835/1500: 1070khs
1000/1500: 1080khs
Edit: Tahiti bin for others to try.. Download link
Then there obviously is some problem with my kernel, Tahiti and the original djm34 miner.
I've just tried running my modified lyra2re miner on the Tahiti cards and it runs at the same speed as you are reporting.
Thus it looks like my optimizations are not effective on Tahiti as they are on Hawai.
That's bad but partly expected.
It's not the end of the story, though, because I've used 14.9 to compile for tahiti which is worse then both 14.6/7 and 14.12 for mining.
I will try with another driver later.