Here is a quote from kano:
It seems to be limited to 2 boards per SPI channel. More tends to get all sorts of errors.
Will look into resolving that ... one day.
Kind of a bummer Most of my rigs have more than 2 boards per SPI channel so :\ yeah..
After a few minutes of running with the bab-options set on my v1.2 rigs it still seems that performance is not consistently equivalent to that of chainminer. That may have something to do with the quote from kano above.
Another thing is I'm not sure if cgminer turns off dead or "zombie" chips like I would when manually editing the chainminer best.cnf file. By zombie chips I mean those that no matter what always hash at a pitifully low hashrate (0.05 to 0.10).
It does shut them down. Check the driver for BAB_BAD_DEAD. This is set to BAB_BAD_MIN * 2 by default. I have cgminer running on a full rig.
The display tells you exactly what's going on with your rig:
0: BaB 0 : 4.16.256 B:034 D:000
BaB 0 4(banks)16(cards)256(chips)34(bad_min)0(disabled)
Here's a very naughty rig:
0: BaB 0 : 4.13.200 B:008 D:025
Cgminer doesn't seem to like the cards set to .85v. The same cards freak out bfgminer.
You can also decrease the time necessary for testing by changing the history setting to something like 120(s) from the default 300(s).