I have my i5 750 on an MSI P55GD65 mobo with a bclk of 200, the vcore is at 1.178V, PLL is at stock, and VTT I raised up the most, although I forget the value right now I think it was 1.6 or 1.7V (basically I think it was a 0.2V increase). I'm running at 3.6ghz (200x18). I haven't tried 4ghz yet since I don't have a reason to do it but from what I've read the VTT would have to be up around 1.8 or 1.9, PLL doesn't have to go up much (unless I misunderstand, but it's related more to QPI than CPU speed - so related to FSB) and then vcore might be around 1.2V.
Also, I wasn't aware the i5 650 could use hyperthreading, I thought that was only in i7s.
Anyway I hope I've helped a little.