Stock is 1.8 according to the stick but bios set it to 1.90 and I have left it at that. Have had it as high as 1.975v. Going to try and see what happens at 423fsb again. Last time I tried it I ended up with 1.975 on the memory and 1.41 on the NB (in bios, 1.3x in windows) and it wouldn't lock up in OCCT anymore like it did with less V on the NB and DIMM but it would crash within 10 minutes. My goal was 3.2ghz and I'm very close. I have set timing back to 5-5-5-18 like it is supposed to be and ran OCCT for 15mins at 419fsb and was fine. I read on a forum where someone hit 1000mhz with this memory using 5-5-5-12 and tRFC of 52. A review on newegg says it's tough to get 850 out of it but another said he was running at 950 using 2v. Some of the revisions of this has the D9 micron but that was in the earlier revisions and there have been 7 according to http://ramlist.ath.cx/ddr2/
which seems to be down this morning.
Setup I am running now.
tCL: 5 (default)
tRAS: 18 (default)
tRFC: 42 (default)
DRAM Speed: 333/667 1:1 (400/800 unstable)
CPU VID Special Add: +37.5mV (1.252v)
SB: 1.510v (default)
CPU VTT: 1.10v (default)