In reply to a post by cheshire_man:

Just looked at the PSU.

It's a Coolermaster RS-500-PSAP-J3

DC Output   |   +3.3V   |   +5V   |  +12V1    |  +12V2  |    -12V    |  +5VSB   |
            |    22A    |   20A   |   20A     |   20A   |    0.8A    |  2.5A    |
Max.Output  |          130W       |         360W        |    9.6W    |  12.5W   |

Your existing PSU is a very branded version, around 500W, and its +12V (via its dual-rails V1&V2) has a total of 40A (not continuous) which should be good enough in most cases. However you still cannot guarantee in its "dynamic states" (i.e. spurious not measurable by ordinary multimeters due to system noises or design degradations etc) would not have caused sufficient voltage-spikes on your above DC rails, causing your MD to fail! Therefore the only way, as I see it, is to try another "known good" PSU with similar or better ratings both in terms of DC Rail-Voltages, max currents and power!
Good luck

One minor question - what does MD mean in this context? Perhaps an alternative to mother board?

Yeah! My finger trouble when typing this response! Should have meant "MB" which means your motherboard instead. Sorry and good luck in finding the root/s of your BSOD.

Getting a new PSU to test is a good idea.

But try and get one that has 1 12v rail and not 2 or more

something like this

http://www.ebuyer.com/264509-ocz-zs-series-550w-80-b...

or if you want cheaper

http://www.ebuyer.com/268696-coolermaster-450w-gx-ps...

In reply to a post by Seansmit17:

or if you want cheaper

http://www.ebuyer.com/268696-coolermaster-450w-gx-ps...

Does'nt mean wanted to hijack the original mail!
This particular PSU should be good and, particularly it is from Coolermaster 450W GX PSU brand as well. However the Ebuyer's still does'nt mention WHAT are the maximum current ratings, particularly the +12V rail, for each voltage rails! But there are 4+4 pins been allocated to the +12V rail in its PSU connector , which means the +12V maximum output currents may be significantly HIGH by design, or is it??

Edited by deleted (Mon 31-Oct-11 10:47:05)

coolermaster silent pro M line is a solid psu to choose and it has single 12v rails meaning you less likely to hit an issue with overloading a rail.

IF (big if) it's the PSU, you can monitor the voltages on the exotics tab of speedfan.

Try disabling (If onboard) or removing the NIC and substituting with a known good PCI card.

The NIC is on board, is a Realtek RTL8111E chip.

There is a BIOS setting "Onboard H/W LAN" currently set to Enabled. I presume set it to Disabled then the plug in card should be found and driver can be loaded.

I'm continuing to try things, but still getting BSODs and the occasional freeze.

Some recent observations:

The PC froze today, as usual the mouse laser went out and the whole system was dead. Screen still ok but no visible disc activity or response to caps lock etc. As it happened I had headphones on at the time and as soon as it froze I realised that there was a hum through the headphones, similar to a mains hum.

Any diagnostic significance?

Having earlier today (after the freeze) reseated the memory, the graphics card, and one of the power connectors (couldn't get one of them off so didn't do that one). Then maybe an hour or so later the screen flickered and a message box appeared at bottom right saying the graphics card/driver/subsystem (can't remember which) had stopped and had recovered.

Any diagnostic significance?

I'll be talking to the local shop that built the system in the next few days, I have a very good relationship with them. I'll be asking if they can try a different graphics cards (any VERY safe recommendations?); similarly try a separate LAN card and disable the onboard LAN chip (again, any recommendations?); possibly even try another PSU.

Any other constructive thoughts gratefully received.