Hey man, I posted a 280x config that some of the guys here on the forum claimed worked for them as well. Not sure for the 290 though. Give this one a shot on your 280x:

ultracoinminer -o ultra.leetpools.com:3333 -u user.1 -p x --scrypt-jane --sj-nfmin 4 --sj-nfmax 30 --sj-time 1388361600 --thread-concurrency 8192 -g 2 -I 13 -w 256 --temp-cutoff 90 --temp-overheat 85 --gpu-powertune 20 --gpu-threads 2 --expiry 1 --queue 0 --no-submit-stale