Help, blown PSU / other problem?

[Oakey]

I just went from a socket 754 A64 3000 to Socket 939 A64 3000. Both motherboards are DFI nf3 and nf4 respectively.

After installing the new nf4 I came to power up and there was nothing. Assumed mobo was DOA so tried connecting power to DFI nf3 and the same, nothing. So I tried a different power cable and the red LED came on. Tried it in the nf4 DFI and as soon as I plugged the power cable into the back of the PSU (Tagan, 430w I think) there was a bright flash and the lovely smell of roast PSU.

Now the tricky part. I didn't have the power cable connected to the motherboard at this time, only the 4-pin 12v connector, a molex connector, and the fdd style power connector (both a requirement on the DFI 939 mobo for some reason) so I'm at a loss as to why the PSU blew, I hadn't even pressed the power on!

The onyl thing I can think is that the molex, fdd connector and another molex plugged into one of the 7800GTX connections were all on the same cable although I can't see why this would blow a PSU.

Any suggestions as to what could cause this? As far as I can tell there's no shorting problems with motherboard and case (it's identical to the previous setup) and everything was connected as before, the only difference being the nf4 uses extra power connectors whereas the nf3 does not.

I've just ordered a new PSU however I'm a little paranoid it'll get blown up immediately again so any help is appreciated.

[ifyouknowme]

thats weird might be a dodgy compnonet somewhere but the psu should shut down when shorted

[Dougal]

Well, number one, you shouldn't have left the PSU plugged in.

What probably happened is the board tried to draw power from all the connected sockets and drew too much from certain rails because you didn't have the 24 pin connecter in.

NEVER EVER (EVER) leave the PSU plugged into the mains when you are connecting it to the motherboard.

Recipie for disaster.

[Oakey]

It still seems odd it would blow like that. If the new PSU blows then I should assume there's a serious problem with the motherboard? I've stripped the system down and ll is left is the motherboard in the case. I saw nothing that would cause any problems during dismantling

[Dougal]

The problem as I said was that you hadn't connected all the cables.

When a motherboard is plugged into the PSU which is plugged into the mains it runs a series of low level circuit checks.

Hence the reason for the Green LED and on some boards a Red LED.

Checking for correctly connected cables.

You'll probably be able to get a replacement PSU.

[Oakey]

Fair enough. But can you explain why things seemed dead before I replaced the fuse in the power cable? There must be a reason the fuse blew?

[RavenNight]

Could just be a faulty supply, thats happened to me before. PSU worked perfectly for over a year but when it was reinstalled after cleaning it, it went bang.

Fuses do just go sometimes, I think they wear out in some way. I try just putting the power cable into your new PSU and turning it on first (ideally use the power cable that comes with the PSU) totally outside the case to check thats everything is fine.

[Oakey]

Could just be a faulty supply, thats happened to me before. PSU worked perfectly for over a year but when it was reinstalled after cleaning it, it went bang.

Fuses do just go sometimes, I think they wear out in some way. I try just putting the power cable into your new PSU and turning it on first (ideally use the power cable that comes with the PSU) totally outside the case to check thats everything is fine.

That's the plan. I'll check it with the old DFI first. If that works, try it in new one, if this PSU blows then the problem lies with the motherboard

Then I'll have to RMA two PSU's and a motherboard. Joy.

[RavenNight]

I'd be really suprised if its your mobo, DFI are meant to be super reliable. Plus who doesn't enjoy RMA?

[hitharder]

if u want i could create a tester module that when u set it up (will require building) it tests all ur components work together bfore u put them in ur case.

[Oakey]

if u want i could create a tester module that when u set it up (will require building) it tests all ur components work together bfore u put them in ur case.

What does that involve exactly? Any pics?

However, the CPU, RAM, GFX, et al, should all work together fine as a mate online has the exact same setup.

I'm hoping it was just a dodgy PSU / plugging it in when it wasn't connected to the board. I can't see any reason why the motherboard would have some kind of issue where it could blow PSU's.