i have some 270s mining x11 just fine getting about 1.9Mh/s per card, getting shares.  

my 290x is running at 4.11Mh/s, but i am getting no accepted shares.
here are my settings:

"intensity" : "15",
"worksize" : "128",
"kernel" : "x11mod",
"lookup-gap" : "0",
"thread-concurrency" : "24550",
"shaders" : "0",
"gpu-threads" : "1"

all i keep seeing is diff set to xx and stratum detected new block

help?

edit: one thing i should mention is that the pc with 290x has the latest AMD drivers installed, but it seems like thats a good thing