Motherboard shorting out power supply?

[cbuchach]

I also posted this in the General forum but was hoping for more specific advice here as this is the best I can tell a motherboard-power supply issue.

I need to try to explain the strange issues with my machine. I have an Asus P5Q-E with and an overclocked Q6600 (413*8 at 1.500V) that has been working well for some time (8+ months). I normally leave my machine on 24/7 but went on a long vacation and turned the machine off. I came back from the 11 day vacation and turned on my machine and nothing. The MB lights were on and tried pushing the onboard power and reset switches with nothing. I tried a few things but eventually ended up trying a different PS (only for a few seconds to see the fans spin up) and the machine turned right on. So my power supply was a few years old and I figured it had died.

So my new replacement power supply arrives a few days later (a Fortron source 700W) and I plug it in and the machine boots right up. I had cleared the BIOS so needed to re enter all my settings and then got into windows with no problem. I then went about resetting my FSB speeds and voltages in the BIOS and booted into Memtest to ensure stability. I came back and the screen was blank, the machine was powered down but there were lights on my keyboard. So I thought maybe the overclock was bad and restarted with nothing. I became worried and again cleared the BIOS and pushed the power button-----nothing-----I sat starting to get concerned and out of the blue the machine turns on---what the hell??

So I got back into windows and started using the machine. I then rebooted and made what may have been the mistake of re-entering my overlclock settings and restarting. The machine again booted into windows. I went away for a while (20 minutes) and came back and the machine was off.

I since have been unable to get the machine to start with the new power supply (I also tried the old one with nothing). I did have another older power supply available and have since connected that for a brief second and it still works. With the other two dead power supplies, the motherboard lights are on when it is connected but the machine absolutely does not turn on, the fans don't spin and nothing happens.

So it seems to me that my previsouly stable computer with absolutely no issues has now apparently started destroying now two power supplies? Does anyone have any idea what is going on? I am assuming this must be a motherboard issue--but why and why now? I am thoroughly perplexed and what appreciate any possible help.

Also, since this may be a shorting issue, does anyone have experience replacing power supply fuses?

 

[HOOfan 1]

If absolutely nothing is happening...it could be a bad power button/switch.

Try bypassing the switch Look here

If that doesn't work try jumping the PSU. remove the ATX connector from your motherboard and it might be wise to unhook anything but a few fans. Then use a paperclip or some sort of conductor to short the terminal connected to the green wire to the black terminal next to it. The PSU fan should spin up.

 

[cbuchach]

Originally posted by: HOOfan 1
If absolutely nothing is happening...it could be a bad power button/switch.

Try bypassing the switch Look here

If that doesn't work try jumping the PSU. remove the ATX connector from your motherboard and it might be wise to unhook anything but a few fans. Then use a paperclip or some sort of conductor to short the terminal connected to the green wire to the black terminal next to it. The PSU fan should spin up.

Both power supplies did work and then stopped. I thought about the case power switch--fortunately the P5Q-E motherboard has an additonal power switch soldered to the MB which made no difference when pressed.

 

[HOOfan 1]

you mean you tried the paperclip trick and they spun up and then stopped?

 

[cbuchach]

Originally posted by: HOOfan 1
you mean you tried the paperclip trick and they spun up and then stopped?

I clicked on the link on the site you posted for the "paperclip trick" and it pulled up a link for troubleshooting a faulty computer case power switch by directly shorting the power pins on the motherboard (they used a flat head screwdriver instead of a paperclip). I have done that before and in my case I have tried three different ways to start the system 1.the computer case switch, 2. the power button soldered to the MB, and 3. by trying a flat head screwdriver directly on the MB power pins --- none resulted in the system starting, so I know it isn't the power switch.

I did check out some of the other links at that site and they mentioned that a PSU can "partially fail" meaning MB lights can be on but the PSU can still be bad. I am wondering if that is my case and the now two bad PSU's have partial failures--exactly caused by what I don't know, but my best guess if the motherboard.

 

[cbuchach]

Originally posted by: HOOfan 1
If absolutely nothing is happening...it could be a bad power button/switch.



If that doesn't work try jumping the PSU. remove the ATX connector from your motherboard and it might be wise to unhook anything but a few fans. Then use a paperclip or some sort of conductor to short the terminal connected to the green wire to the black terminal next to it. The PSU fan should spin up.

I just more closely read exactly what you meant by the papclip trick and will try that when I get home today. By terminals I am assuming you mean shorting the green and adjacent black connectors on the ATX power plug?

 

[cbuchach]

Originally posted by: HOOfan 1
you mean you tried the paperclip trick and they spun up and then stopped?

OK, so I tried the paperclip to jumpstart the old PSU and it did work! So I now really don't know what is going on and am going to do some more testing the the MB and the old power supply to see if it will again start--I'll let you know.

 

[cbuchach]

I plugged the PSU back into the motherboard on the desk out of the case. Although the PSU did work with the jumpstarting by the paperclip it still was dead and the motherboard would not start.

So I think somehow the motherboard is bad and am going to RMA it to Asus for a replacement.

 

[cbuchach]

So I have one more question for everyone.

I now have another new power supply and am waiting on a replacement for my Asus P5Q-E board and am actually a little nervous about connecting everything up again. I will just plug in the CPU, RAM, and video card on the benchtop for the first runs. The only things that will be the same as the last system are the CPU RAM and video card, and I can't imagine that one of those components could have been the cause of the PSU failures right??

 

[HOOfan 1]

No, I can't either...I am still not sure it was the PSUs that failed, and not just your motherboard

 

[Binky]

I'm guessing here, but have you considered the motherboard battery? The only thing that changed for you is that you went from never leaving the system off, to leaving it off for an extended period. I don't really remember what happens when a MB battery completely dies, but it's worth a look.

 

[cbuchach]

Originally posted by: Binky
I'm guessing here, but have you considered the motherboard battery? The only thing that changed for you is that you went from never leaving the system off, to leaving it off for an extended period. I don't really remember what happens when a MB battery completely dies, but it's worth a look.

Well, the system was plugged in on the MB was powered which keeps the system time and such up to date. The MB is only also a few months old and the battery should still be good, but thanks for the suggestion.