try to remove: -w 256, --lookup-gap 2, --thread-concurrency 32765, -I 13
a bigger psu? 300W per card = 1200W, you are right at the limit.
an r9 290 can make 450 with a bit of overclock, but not in your case, cause of not enough current.
thanks I know I'm at the limit, will upgrade to dual psu soon. nice to know that the settings are not bad anyway.
Tried without -w 256, --lookup-gap 2, --thread-concurrency 32765, -I 13 and it's +- the same.