ok as far as defaulting to 166 it seems it only does this when running 512mb sticks. I tried 2x512 of pc3500 Mushkin L2(bh-5), OCZ pc3200 EB, OCZ pc3500 Gold, and Corsair pc3200 XMS(bh-6). All would default to 166. The Mushkin would be able to have timings changed and be set to 200 mem, but it would not overclock worth crap. At 3.2vdimm I would top at 220 2-2-2-11. These sticks did 267 at 3.3v in my K8Npro. Now My XMS were also able to be changed and would do 230 at 3.2vdimm 2-2-2-11. Same sticks in the K8Npro did 245 at 3.3vdimm. My OCZ EB would not be changed from the 166 mem option. Anything and they would not post. Now these same sticks would do 262 at 3.2v 2.5-2-2-11 in my K8Npro.
Now I was about fed up, but decided to try my 2x256 sticks. pc3500 OCZ Plat ltd. edition(bh-5), pc3500 Kingston HyperX(bh-5), and pc3700 OCZ Gold rev 2. All defaulted to the 200 mem option, and had all timings changeable. All would run same speeds they did in my K8Npro. Right now the OCZ plats are running 255x10 2-2-2-11 at 3.2v no problems.
Now I really don't have any answers, but wanted to throw my findings into the ring. All of this was done using either bios F1 for the K8NSpro, or F2 for the K8NSNXP. I found the F2 bios actually to be a little worse.
I am going to be trying the beta bios' posted here today and see if they make any difference. I will report back.
BTW as far as temps, It's funny but bios F1 for the K8NSpro will show 42°c but F2 for the K8NsNXP will show 28°c. Now when using MBM I found I was able to show both of these temps. I am figuring one is socket temp, and the other is on die temp. I do know that the K8Npro reported the lower temp as cpu temp. It usually hovered around 25-29°c in my hot apartment. TYhis is with good watercooling.