Bad PSU?

[jaylek55]

Having some trouble with a computer I support. For some unknown reason, the computer refuses to power on via the power switch unless you powercycle the PSU (old Sparkle that came with the case) down first. Once you cycle it, the PC works just fine. No issues or lock-ups, etc. The PC even shuts down fine. But once it shuts down, you have to cycle the PSU to get the computer to power on again.

I've never experienced this sort of problem before, so I tried another PSU. I have an old Enermax which as far as I knew, was in working order. It's taken a seat in storage since it isn't up to new power specs (20 + 4 pin connector). I tried hooking it up to the computer. Plugged just into the mobo alone and when you turn it on, it doesn't power on then off, like most PSUs do. It simply stays on. No booting occurs or anything, just continuous power to the motherboard.

For now the old Sparkle is still in the PC since aside from cycling it, it powers the PC just fine. But I need to know if this issue is indicative of a serious problem. I have another PSU (pulled from an Antec case about a year ago) which I can try, but I won't be able to try until later this week. In the meantime, I'd like to see if anyone may have a clue as to what's going on.

K7T Turbo Limited Edition
1GB of Mushkin RAM (2 x 512MB)
Gainward 4200Ti
2 HDDs
CD-Rom
Plextor CD-RW

Thanks.

 

[kmrivers]

i had that problem on an abit nf7s. it was because i had a usb header plugged in the wrong way or something like that. just check connections even things that don't have anything to do with power. well the usb does... it was messing the the 5v somehow. sorry it was a while ago.

hope that may help.

 

[jaylek55]

I unplugged everything and reconnected everything when I was swapping the PSUs. But come to think of it, when we booted the PC after the PSUs swaps...the webcam that was attached before suddenly acted like it had never been plugged in before. XP acted like we added new hardware. I'll look into it. Thanks.

 

[jaylek55]

Bump for more ideas.

 

[Jiggz]

Using the same old Sparkle, disconnect both of the cd roms and other hdd except for the os hdd. Come down to one stick of ram, and disconnect all other peripherals. All you want is a basic PC with a stick of ram, a video card and a hdd, and then try again. If the system powers up the PSU could be the problem. Now don't jump out yet. Try reconnecting the peripherals one at a time and then testing along each step until the problem show up again. Now disconnect the last peripheral you re connected (which caused the problem to show up again), and also the one before it. Now reconnect the last peripheral that caused the problem to show up again. If the problem shows up again after you reconnect, the peripheral could be bad. If the problem does not show up again, the PSU is under-rated to start all of your peripherals. Remember, the largest demand of current happens during boot time. Since the PSU can barely support the starting current requirement, it stalls. By cycling the PSU, you are reducing the starting current since some of the peripherals are already pre-started (capacitors still charged and motors still winding down) by your last attempt to start it.

 

[jaylek55]

I'll try that. Thanks.