Windows 7 - Did my mobo or PSU bite the dust? kb/m lock, no boot, fans run when of

Earlier today I get back to my computer and it looked like it was frozen, because the mouse and keyboard didn't work. So I rebooted and it got into Windows normally, but the kb/m became unresponsive again. And I new it wasn't the system that was frozen because the connectivity indicator was animating. And each time I booted the kb/m became unresponsive at a predetermined time, whether I was in the Windows sign in screen, the BIOS setup, or running on the windows installation CD.

And in between these times it seemed like it had trouble starting up. Sometimes when I pressed the power button the fan would just give a little wheeze and nothing would happen. Later, pressing the power button did nothing at all.

Then one time I tried unplugging and replugging in the PSU it started acting goofy. Now whenever it's plugged in to the outlet, it emits this high pitched sound. And if it's plugged in to the mother board, its own fan and the CPU fan automatically start going, even though the computer isn't on.
What do you suppose might be wrong with them?

Motherboard: Chaintech VNF3-250
PSU: Thermaltake Purepower HPC-420-302 DF

Hi,

Your in a chicken & egg place here, but I would suggest the power supply first place to start as that is the cheepest to investigate.

A power supply of only 420W does seem a little low though?

Without proper tools, it can be difficult determining whether it is a bad PSU or a bad motherboard.

I'd first try to come up with another PSU to swap in temporarily to see if the problem disappears.

Any visible signs of a bad motherboard, such as bulging capacitors?

Chaintech is a bit of a dodgy brand.

it might be that the kb/m both are malfunctioning and if youre using ps2 ports man that CAN freeze windows i had the problem way back..and if youre not using ps2 ports well the usb ports might have some problems and the power supply too cause of the fan..

If this is the power supply you have,

Roundup: 14 Power Supply Units from Thermaltake. Page 3 - X-bit labs

I'm surprised it didn't blow up when you first connected that GTX 460 to it. With only 18A on the 12V rail I'm surprised that it would even boot with that card installed.

As the others have already said start with the power supply, and hope that when it died it didn't take anything else with it. And from the sounds of what you're describing, it may well have killed the motherboard.

I should clarify that i have two computers, and the specs in my profile are from the other, slightly less ancient, one.

So you're running that GTX 460 on an even worse power supply then.

And to determine whether it is the motherboard or the power supply in the other, either try the power supply on another computer or try another power supply in the suspect one.

May find that the power supply is fine 9or as fine as that thing can be) and what happened is that a voltage surge or something hit it and it let it through, and ended up killing the motherboard.

If it helps any the last three computers I worked on with the same symptoms (fans spin, and nothing else), it was a dead (or mostly blown) motherboard, all from a power surge that the power supply should have stopped (or died itself from).

I suppose I'll have to get a new PSU anyway since I don't have any other 20 pin ones to test with.

So a Startech AXT2PW550PRO is no good for a GTX460?

I always recommend, Corsair, Seasonic or Antec PSUs.

You might also want to consider the cables within the CPU. I experienced the same thing with our desktop due to a faulty serial ATA cable.