It just won't OC

Ok guys I'm totally confused here, and can't figure this out.
I had a CPU die on me (the Tbred) and at first I thought it was the mobo because of some tests I didn't do right, anyway I got this NF7 rev. 2.0 and now use my old 1400 Tbird. This chip ran at 1630 @ 1.85v in the past without problems, now it won't even do 1550MHz stable at 1.85v, it will just BSOD while loading windows, or just reboot if its not in windows yet.
It also refused to post at any voltage setting over 1.85v. I've thought it might be a high FSB problem but at 136x11.5 (1553) I still get the same thing. It will only run stable at 1400 or a bit over, like I'm running now in sig. I tried everything I could think of, also tried enabling CPU interface (although I know it does nothing) and nothing works, it just keeps being unstable. I thought about PSU, but my voltage lines never drop under +5 or +12v, and are pretty stable.
Can anyone enlighten me please, this is my first Abit and first nF2 board, my last one is A7V266-E, maybe I'm just doing something wrong?
Basically its not the RAM, its not the high FSB, its not the voltage either, as it did 1550 @ 1.8 w/o a problem, it shouldn't be the PSU.

It "could" be the ram, some nforce boards are fussy with what ram you put into them. I'm not familiar with the board you're running; is there vdimm voltages you can increase too?

I've tested both at totally stock RAM speed (133MHz) and at 209MHz, same result, with any vdimm voltage and with any multiplier. The machine runs completely stable at close to CPU stock speed tho, that is what puzzles me.

There's the FSB Spread spectrum in the BIOS (I think that's what its called) and another option, they both are set to 50%, maybe disabling them would help? If its the same as CPU Spread spectrum on VIA boards, that helped my stability before.

check the CPU Throttling , this should be disabled aswell as the other 2 , dont remember what they are off hand but those hacve top be disabled to do any decent OCing.
what are you using to see the voltage, and not seeing it above 1.85? bios or MBM or whatever you use ?
Ram is very touchy with NF7 , in mine I can get 404 (202fsb) 1:1 in the first set of Dual channels but not the second , I cant even hit 200 fsb with those and I am using Mushkin 3200 Promo Build(green pcb)

FSB speed is not a problem, I think I've hit the limit of my crucial RAM.
When I select vcore higher than 1.85, like 1.875 and higher I just get no POST. I will try setting those settings to disabled when I'm next home on thursday.
CPU throttling was set to disabled from day one

what are the temps like anything above 57C my chip becomes unstable and restarts

My temps are posted in my sig, its running at about 40C, give or take 1-2C

oh yeah sorry maybe it just dont want to run at those speeds anymore ?

I dunno, its strange that it doesn't want to do it anymore. it did it fine couple of months ago.
What is your FSB Spread spectrum set to?

disabled

Does it really make a noticable difference in OCability?

Well I tried it running AGP and FSB spectrum disabled, and it still does the same thing. I'm just about to give up, unless someone has a suggestion?

I wouldn't completely rule out the power supply yet. The NF7 derives its core voltage from the +12v rail, as opposed to the A7V266 which derives it from the 5v rail. For a successful overclock on the NF7, you'd need a beefy 12V rail on your PSU. You can't really trust motherboard voltage readings either. Try a higher voltage and a lower speed and see what happens.

hmmmmm
I guess I will try that, thanks for the tip.
bah I'm gonna get that digital multimeter I put my eye on in a local store, I've been stuck with a small crappy, half not working, analog multimeter for years, its time for an upgrade.
This way I'd also be able to accuratly measure the PSU rails.

Just stick the multimeter wires into the molex for +12 and +5 measurment, under full CPU load ofcourse, right?

Yeah. What power supply do you have?

I got an Enermax 450W. It seems good enough
Its a unique unit, was taken out of a PSU which had two single PSUs in one, if one failed, other kicked in, its a server PSU.
Had to be moded a bit and dialed way down, because it output 5.7v on the +5v line as it had a diode in the way of the output. so while dialed way down it still holds pretty well... All I can say is I wish the NF7 used the +5v line for powering the CPU, this thing can kick out 40As on the +5v line.

*EDIT:* Here's a screenie: