Yes, Darkcoin only (hum, I did not use the SpH miner to mine scrypt, but with other miners, no problem), R9 290 only.
Since darkcoin is no scrypt, whats the matter?
Or do you mean: you are only mining darkcoin with sph-sgminer?
Would be nice to test scrypt with sgminer.
Kernels should be the same, pls give it a try!
I'd confirm that sgminer scrypt algo works as intended, no ten percent drop over time or another unusual glitch.
If someone could check the X11 algos with another miner to look if the issue is sph-related or driver related, would be very helpful.