Random crashes, PLZ HELP!

[CowMan]

Ok, here's the problem. At least once a day I get a random reboot or crash. Usually it's a total restart without any warning but sometimes I get the BSOD and the message: DRIVER_IRQL_LESS_OR_EQUAL
STOP 0x000000D1 (0x00000000, 0x00000002, 0x00000000, 0x00000000)
BEGINING DUMP OF PHYSICAL MEMORY

My system specs are in my sig, so that's what I'm working with. My temps are around 40C at all times so heat isn't the problem. The power supply never wavers, so it's not that, and both sticks of ram (after lots of testing) appear to be fine. I thought it might be the RAM at first, so I tested it in my old computer which houses a Duron 850. I ran MEMTEST86+ and Prime95 for a couple hours for each setting I could think of. It ran flawlessly with the RAM at 100 and never crashed. Then I put my 2500+ in it and ran it at 100 and then 133 (this particular mobo doesn't support above 133 fsb) and it ran flawlessly as well. So now I've put everything back in my normal system. Here's what I've tried doing so far:

RUN MEMTEST86+
1) CPU and RAM at 166FSB -> Crashes within 5-30 minutes
2) CPU at 133, RAM at 166 -> Stable for at least 3 passes (stopped after that)
3) CPU at 133, RAM at 200 -> Stable for 8 hours (never crashed)

Here's the real weird thing. After running the CPU at 133 and the RAM at 200 for 8 hours without fail, I drop the RAM back to 133 to match the FSB, go into Windows, and BAM! I get the dreaded BSOD within 10 minutes. Honestly now, wtf?!? I don't have access to a spare mobo, 2500+, or more RAM without buying it. How can I tell whether it's the RAM, CPU, or motherboard now?! Please help!


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Barton 2500+ (stock)
Leadtek K7NCR18-D nforce2
2x256mb Geil pc-3200
Ultra XConnect 500W PSU
WD 80gb SE
BFG GeForce 6800GT OC

 

[endyen]

1- Check the north bridge hsf, clean it, and see how warm it is.
2- Raise the north bridge voltage, if that is an option on your board.
3- Raise the memory voltage, v-dimm, to 2.8
4- I believe that mobo uses a t-diode under the chip to give core temps. If it is making poor contact... Try putting your finger on the hs, to see how hot it is.

BTW, all of these are mobo related problems. so I'm guessing that I think the problem is with the mobo.

 

[CowMan]

1- I replaced the passive northbridge heatsink with a thermaltake crystal orb soon after I bought the mobo. It's not overheating or anything and it's pretty devoid of dust.

2- Raising the northbridge voltage isn't an option on the motherboard.

3- Raising the vdimm voltage isn't an option either. Damn.

4- When I first got my barton in this motherboard, it would crash soon after booting up due to overheating. This was later found to be caused by improper seating of the heatsink (it was backwards and not making good contact). After correctly placing it on the CPU, it was stable for a solid 2 years until now. The heatsink hasn't changed, I've got the system at 150 fsb right now and it's cold to the touch. Is there anything else it could be?

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Barton 2500+ (stock)
Leadtek K7NCR18-D nforce2
2x256mb Geil pc-3200
Ultra XConnect 500W PSU
WD 80gb SE
BFG GeForce 6800GT OC

 

[endyen]

Take a look at the caps close to the chip. If they're tops are not flat, or they are leaking, that would be your problem.
Do you have MBM5? Get it, set up to run a log, every 10 sec or so, then crash the computer. This will give a clear picture of voltages, and temp.