ASUS M2N32 SLI-Deluxe failure

[StevieBates]

Here is my current (home-built) spec, in an ATX case:
M/b - ASUS M2N32-SLI Deluxe
CPU - AMD Athlon 64 X2 4600 AM2 2.4GHz
Mem - Corsair 1GB XMS2-6400 240DIMM CL5 (*2)
Gfx - Sapphire Ultimate Radeon X1950Pro 256MB GDDR3 Dual DVI
O/S - Windows XP Home SP3
Drives - Sony IDE DVD; DiamondMax 10 and Seagate Barracuda SATA HDDs
The system switches off after 2-3 seconds. If I disconnect the 4-pin 12v, the PSU and CPU fans stay whirring so I suspect this is a motherboard failure on the 12v rail. I therefore need to replace the m/b and, since I am an impoverished student, I'm hoping to only replace the m/b (at least for now).

Unless someone wants to correct my diagnosis what is a good AM2+ that will take most of those components?
The pokiest software I'm running is Company of Heroes.
All thoughts welcome, ta!

 

[o1die]

Please list your power supply make, model, and 12v rail, usually listed on the label or at newegg.com. Chances are they carried it at one time, and the specs are still on their website.

 

[StevieBates]

Well there's a story there (that I hadn't wanted to bore you with). I did have an Enermax Liberty (ELT500AWT) (22A) but that died and so I briefly had the original cum-with-chassis Bestek ATX350F1H (18A) in until last weekend when I installed an Antec Earthwatts 650 (38A). I suspect damage was done while the underpowered Bestek was in use.

The Antec, incidentally, has developed a fault: the on-off switch on the unit will not switch to off. I'm putting this down to coincidence, but mention it for the sake of fullness.

 

[o1die]

http://www.amazon.com/Asus-M2N-SLI-Deluxe-nVIDIA-Motherboard/dp/B000FVNWRC/ref=sr_1_7?s=electronics&ie=UTF8&qid=1321655335&sr=1-7
http://www.ebay.co.uk/itm/AMD-Athlon-64-X2-4200-CPU-and-ASUS-M2N4-SLI-NF4-Motherboard-complete-package-/280771421479?_trksid=p4340.m185&_trkparms=algo%3DDLSL%252BSIC.NPJS%26its%3DI%26itu%3DUCI%252BUA%26otn%3D10%26pmod%3D300604774690%252B300604774690%26po%3D%26ps%3D63%26clkid%3D4291048216946083034.

 

[o1die]

Nokturnal at anandtech's for sale forum has an asus m2n sli for only $35.