Nvidia+CudaMiner vs. ATI+SGMiner - Very Different Reject Rates
I have both Nvidia and ATI cards and I am seeing a very large discrepancy between reject rates.
GTX680+CudaMiner @ 300 KH/s => 0.01% reject rate
GTX780Ti+CudaMiner @ 700 KH/s => 0.16% reject rate
R9 290X+SGMiner @ 913 KH/s => 8.0% reject rate
All of the above are on the mega node for higher difficulty. There are 0 HW errors being reported. So contrary to what one might expect, the faster the hash rate, the higher the reject rate. That makes no sense at all. And while even 0.16% reject rate seems fairly trivial, the 7.9% reject rate with SGMiner is most definitely not trivial.
The effective hash rate is thus:
780Ti: 700 * 0.9984 = 698.88
290X: 913 * 0.9200 = 839.96
This slashes the ATI card's advantage by 1/3.
I'm pretty sure this isn't normal.
1) a "feature" of how the pool distributes WUs and assigns difficulty
2) a major bug in SGMiner 4.1.153
3) A consequence of instability in computation time across different WUs that only manifests on ATI cards
4) Something else?