PC doesn't start, without smoking wires!

[Swarbs]

Hi

My PC recently refused to boot. When I pressed the power switch, the lights came on and the PSU and case fans spun briefly (aout 1/4 of a turn) then nothing. I opened the case and disconnected everything but mobo, CPU, RAM and video card. Still no joy.

I then took the 20 pin cable off the mobo and shorted the green and black wires (Power OK and Ground) to manually start the PSU. This worked, and everything started up, including the CPU fan. However, after about two seconds, the red wire in the 4 pin EZ_PLUG to the mobo started smoking like mad! Judging from my mobo manual, this is the +5V cable.

I can still short the green and black wires to start the PSU, and it's fine with everything connected but the 12V to the mobo. It even works fine when I short it with the same EZ_PLUG connected to the video card and the square 4 pin ATX12V in the mobo. But with the EZ_PLUG in the mobo it smokes when I short it, and the fans only briefly spin when the 20pin is in the mobo.

Anyone have any ideas? My first thought was unstable voltage from the PSU, but why does it not smoke when it's in the video card? Or perhaps the mobo is taking too much power from the 5V cable? Tho' the mobo is an ASUS A8R-MVP with JumperFree config - i.e. there are no jumpers on the mobo to set voltage. :confused: Any advice would be much appreciated!

Cheers

Matt

P.S. I had the same problem of the PC not starting when I first bought it. After much fiddling it started working, but I'm not sure what I did to fix it!!

[Swarbs]

Only the 5V wire smokes - nothing comes from the CPU or mobo itself. After the smoking, I checked the CPU, mobo, video card and RAM; and there's no damage to any of them. Even more confused...

Also, I have two sets of EZ-PLUGs coming from the PSU. One of them has two connectors, for mobo and video card. The other has three connectors, for DVD-RW and two hard discs. I've tried both of them in the mobo and they both smoke. It's definitely the red wire, as the others are all fine, cool to the touch after the smoke, and haven't slightly melted (as the red one has...)

[mjc]

Have you measured anything with a multimeter?

[Fruss Tray Ted]

Smoking = Bad for your Health :(
Smoking PC = VERY Bad for PC health :eek:

Need to know what you have for a system. All parts involved.

You've described the symptoms but we haven't seen the patient! ;)

[Whyzman]

Do you have another PSU you could try?

[Swarbs]

Ok, haven't measured anything with a multimeter, as I don't have one! Could try and pick on up tomorrow - how do I go about checking voltages with it?

PC system is:

PSU came with case. Case is Benz Silver Super Midi 400W Silent PSU (USB ATX running at UK 230V)
mobo: ASUS A8R-MVP ATI Crossfire AMD (skt 939, PCI-E, DDR400, SATA2, Firewire, USB2 ATX)
CPU: AMD Athlon 64 3200+ (Venice Core 64 bit, 512k L2 Cache, skt 939, mounted heatsink and fan)
Video: XFX GeForce 6600 SLI 256MB DDR
RAM: Corsair Value Select 512MB DDR PC3200

Only other parts are HD drives and DVD-RW, none of which are connected at the mo whilst I diagnose! The system is currently 13 months old.

Don't have another PSU, but am thinking of picking one up tomorrow. Thing is, when I short green and black in the 20 pin, the PSU fan starts up, and the PSU can provide power to CPU fan and video card with no probs; tis only the mobo where it all goes pear-shaped. Will probably buy one tomorrow and give it a try, but wanted to see if anyone had experience of this problem first.

Cheers

Matt