All I know is that with my X2 4400+ (1.3 BIOS) at the measly 1.4 vcore setting couldn't even do 2.4Ghz. The Opteron does 2.5Ghz (10x250) without breaking a sweat (gonna see if it will go higher) with the 1.4 BIOS. So the 1.4v overclocks nicely and the opterons with their lower operating...
Seems that the DC Opterons are more suitable for this board as I can definitely OC higher with the 170 than I could with my X2. Must be due to the lower operating voltage and the fact that the board gives both CPUs the same 1.40v max.
It's also a shame that under load the CPU volts can drop...
You cannot use an odd number of modules in dual channel mode. You either use 2 or 4 ram sticks. one or three ram sticks results in single channel mode. And as the manual says for dual channel you have to put the two ram sticks in either slots 1&2 or 3&4