Well I am going to disagree with sha about the NB fan. This NB gets hot I would leave that fan on but that is up to you.
Second reading all the post I got lost with all you have done so I would clear the CMOS and start from scratch. When you start from scratch put the RAM on 800mhz. That is what the motherboard supports so that is where I would start. All your other settings looked good except the SB I would just go ahead and put that on 1.5. Then start trying again with just the CPU settings and vcore. Once you get it where you want it then start upping your RAM.
Good luck sorry I really did not give any new ideas. Keep us informed on what happens.
Also, 3.2 might be all you can get out of it. I know that is all i can get stable out of my Q6600.
One other thing to bring up. What drivers did you use for your motherboard?? I know when I first put mine together I was getting random BSOD's because I used the drivers from the CD that came with it. Download the new ones from Nvidia's website if you have not already.
I've tried changing the RAM to all sorts of values. I'll put it on 800mhz and leave it there! Should I still set manual voltages and timings when at 800mhz?
I'm using the latest chipset drivers from nVidia's web site. I was previously using the ones which came with my PC, but I was still getting the same BSOD's back then. I'm also using the latest BIOS firmware.
I was just browsing the Internet the night before last, and I got the same BSOD: IRQL_LESS_THAN_OR_EQUAL... Perfoming dump of physical memory... The PC doesn't have to be under any stress for this to happen. I re-booted, and during the Vista splash screenm where you see the horizontal green progress bar, the PC froze completely. I had to re-boot obviously. Since then, it's been faultless. So even at my current OC of 3.2ghz, it's still unstable. Funny thing is, I like to play games like COD5 etc, and these put a lot more stress on the system than clicking about in Vista, yet I've never had a BSOD when playing games, it only happens during start-up, or when clicking about in Vista, such browsing the net...