Is here any reason why Automatic profile mining 20 Mhash/sec more?
is it just rounding in formula or dbase distributing load better?
Rejection rate with automatic profile is horrible, more workers, more rejections,
maybe it is compensation for higher hashrate.
I have found that I get a slight increase in hashing with multiple instances. I have seen the explanation that multiple instances help fill in very small times where the CPU might be waiting for the GPU before sending it new work, hence the slight increase in hashing with multiple instances as the CPU always has somewhere to send work to without waiting.
I don't get any rejection rate problems, no matter how many instances I happen to be running. I have tested this up to 6 instances per card with no real affect on rejections. I have found, however that worksize is very important when it comes to multiple instances and rejection rate. Could you go to configure miners->edit and edit the phoenix launch string, changing the work size from 128 to 256, then restart smartcoin. I'd be interested to hear if it fixes your rejection rate problems (i run worksize 256 and I'm always below 1%). I've been thinking about changing the default launch string to 256, your confirmation on this could help me make that decision.
Also I added another GPU and CPU load go from 0.8% to 2.6%, is it normal?
Yes, this is normal.