Testing / comparing : Intel D975XBX2 / Asus P5B DX ***56K WARNING***

[KMEI]

Currently doing Orthos on 3.6GHz with the following settings (30min no error atm):
Reference Frequency: 333MHz
Memory Frequency: 667MHz
Timings: 4-4-4-12-2T and 1:1

vCore: 1.575V -- What application do you guys use to measure vCore under load?
vDimm: 2.16V
vMCH: 1.650V
vFSB: 1.375V

I almost received instant error in Orthos with 1.550V -- How much voltage does other guys with the F-batch require?

I'm still wondering about the difference of using 333 ref 667 mem freq and 266 ref 533 mem freq, am I losing performance by using these options? I would be extremely happy if someone could explain this to me.

Any comment would be appreciated though, I'm quite new into overclocking.