Help/Suggestions For Stability Issue

[Gaussios]

Well, heres the scoop.
Three or so months ago I made use of this site and many others to add a little extra juice to my computer. I got a fair amount of extra speed, and was comfortable with the temperatures everything was running at.
I moved back to university about a month ago, and due to excessive noise from all my fans required to keep the temps down, I decided to put everything back to the stock configuration. Problem is, I cant seem to get it there and Im now experiencing stability issues.
To start off with, I'll give a quick run down of my system specs and then I'll describe my problems.

Gigabyte 965P-DS3 Mobo
Intel Conroe E6600 2.4GHz
2 x 1GB Corsair Dominator ram @800MHz
EVGA 8800 GTS S/C 640Mb
BFG 650W P/S
Antec 900 Case

At the peak of my O/C, the CPU was at 3.2 GHz and reached a maximum temperature of 46 deg C, and the ram was on 3-4-3-9 timing (still @ 800MHz) at 2.4V.
The FSB was brought up to 400MHz.

The system ran perfectly stable in these settings even under stress test and long gaming sessions. To bring my settings back to normal, I simple entered the bios and loaded the "fail safe settings"... this is when the problems started. After saving the settings and restarting, the bios failed to POST. I tried everything to fix it, including removing the mobo from case, stripping down to one stick of ram, reset the cmos using battery removal and jumpers. In the end, on a hunch, I went out and bought a 20$ stick of ram and shoved it in in place of my Corsair stuff - I got a POST.
From here I was able to up the dimm voltage back to 2.4V, reinstall my Corsair ram, and restart fine. I thought it might be a problem with my RAM, so the next time I got a failed POST I borrowed a stick of my buddy's Mushkin ram (similar quality - requires 2.1V). The result was no different... the bios still failed to POST.

The cpu settings are all back to normal, and the ram timing is back to standard, but I still need the 2.4V to be able to run my Corsair ram (even just one stick of it.) If I drop the voltage to even 2.3 (or load any of the failsafe/optimized settings, which set all voltages to 'Auto'), I fail to POST again and have to repeat the process of using the crappy ram to get back into the bios settings.

Additionally, when running with everything stock besides the RAM voltage, I have a fairly unstable system. Both my G7 mice (I know its not a problem with either) will periodically cease to function or function very choppy, almost as if I'm playing a very laggy first person shooter, for awhile. A cheaper mouse will continue to work fine even while the G7 is not.
Further, every now and again I get a random blue screen of death which appears and disappears so rapidly I cant read anything... this is followed by a restart, and a fail to POST. I either have to switch to the crappy ram, or else leave the comp for an hour or two before I can get going again.

Im pretty sure its not a problem with the RAM or processor, and Im led to believe it is the motherboard from the mouse problems and general inability to obtain bios posts with anything but low quality 1.8V ram unless I have a large amount of overvoltage.
Ive tried updating to the latest BIOS version and the latest mobo drivers and am now looking for any possible alternate suggestions, be it a possible cause or a possible solution, to fix up the stability of my system. At the moment the only idea I've got is to replace the motherboard, but Im not even 100% certain that is where the problem lies or that it cannot be fixed.

Cheers

[jasfife]

Have you used Memtest? That would rule out the RAM.

[Gaussios]

Yup, ran mem test. Let all the basic tests cycle for a few hours and no failures. Never ran the 'extended test' or whatever its called which stores a value and attempts to recover it several hours later, but I'm feeling fairly confident the RAM is not the problem. I'll run the extended test tonight just to be sure.