I've uploaded a small update v3.1, +5% speed for 290/290X, so CPD for these cards is about 2.5 now. For other cards probably you will see even less improvement, so just wait for better update

After a while starts to give here such data and stops looking for blocks.
R9 290X Tri-x
miner v3.1
══════════════════════════════════════════════════════════════════════════════
Wed Apr 23 22:38:14 2014
New Block: 507483 - Current Diff: 10.816298
Total/Valid blocks: [ 0 / 0 ] - Max diff: 8.916014
[ 4ch] [ 7ch] [ 8ch] [ 9ch] [ 10ch] [ 11ch] [ 12ch]
Total: [ 93K] [ 58] [ 4] [ 0] [ 0] [ 0] [ 0]
ch/h: [ 200552] [124.564] [ 8.591] [ 0.000] [ 0.000] [ 0.000] [ 0.000]
Estimated CPD: 2.1477, Average CPD: 0.0000, Mining time: 00:27
══════════════════════════════════════════════════════════════════════════════
sieve: 128, fermat: 2, total: 136 Total Round Time (TRT): 136
sieve: 128, fermat: 1, total: 136 Total Round Time (TRT): 136
sieve: 128, fermat: 2, total: 137 Total Round Time (TRT): 137
sieve: 128, fermat: 2, total: 137 Total Round Time (TRT): 137
sieve: 128, fermat: 2, total: 137 Total Round Time (TRT): 137
sieve: 128, fermat: 2, total: 138 Total Round Time (TRT): 138
sieve: 128, fermat: 2, total: 136 Total Round Time (TRT): 136
sieve: 128, fermat: 2, total: 137 Total Round Time (TRT): 137
sieve: 128, fermat: 2, total: 137 Total Round Time (TRT): 137
Yes, this problem confirmed and fixed, check my folder on MEGA and download v3.1b.
1.280X solo3.1b
Thu Apr 24 03:14:23 2014
New Block: 507523 - Current Diff: 10.816398
Total/Valid blocks: [ 0 / 0 ] - Max diff: 7.985481
[ 4ch] [ 7ch] [ 8ch] [ 9ch] [ 10ch] [ 11ch] [ 12ch]
Total: [ 27K] [ 25] [ 0] [ 0] [ 0] [ 0] [ 0]
ch/h: [ 139874] [127.279] [ 0.000] [ 0.000] [ 0.000] [ 0.000] [ 0.000]
Estimated CPD: 2.1945, Average CPD: 0.0000, Mining time: 00:11
屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯
sieve: 166, fermat: 148, total: 326 Total Round Time (TRT): 326
sieve: 166, fermat: 148, total: 333 Total Round Time (TRT): 333
sieve: 166, fermat: 147, total: 326 Total Round Time (TRT): 326
2.280X solo 3.1b
Total/Valid blocks: [ 0 / 0 ] - Max diff: 9.128120
[ 4ch] [ 7ch] [ 8ch] [ 9ch] [ 10ch] [ 11ch] [ 12ch]
Total: [ 90K] [ 65] [ 3] [ 1] [ 0] [ 0] [ 0]
ch/h: [ 56971] [ 40.849] [ 1.885] [ 0.628] [ 0.000] [ 0.000] [ 0.000]
Estimated CPD: 0.7043, Average CPD: 0.0000, Mining time: 01:35
屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯
sieve: 166, fermat: 2, total: 180 Total Round Time (TRT): 180
sieve: 166, fermat: 1, total: 178 Total Round Time (TRT): 178
sieve: 166, fermat: 1, total: 178 Total Round Time (TRT): 178
sieve: 166, fermat: 2, total: 179 Total Round Time (TRT): 179
sieve: 166, fermat: 2, total: 178 Total Round Time (TRT): 178
"Less values are better, you can overclock cards or do anything you want to minimize these values."at "Readme!!!.txt" but 1 280X and 2 280X 4CH a lot of difference, speed depends on the minimum value of M? Or 4CH?