Computer Won't Shut Down (possible power supply issue)

[RoyVonBacon]

Hello all, I've been a reader of anandtech for a long time, but never posted here.

I've been building my own systems since 2000, and while I've my share of problems I've usually been able to find answers online. However I have a new problem that is not only hard to diagnose with a google search, but I'm having trouble finding the time to really work on it. So I'll jump right in.

I work overseas for months at a time, and upon returning from my last trip, I found my roommate had unplugged the power chord from my power supply. He had said there was a power outage in our area and that my computer had turned on by itself and would not turn off even after holding the power button for long periods. So I plugged it in and sure enough there was some sort of malfunction with the power button. As soon as the power supply power switch is flipped on, the system powers up, but it does not boot. All the fans immediately start blowing at 100% and the monitor stays in sleep mode. Upon pressing the power switch the system boots normally and the fans go back to regular speed. The computer then works fine till I shut it down, where it goes from the regular blue windows shut down screen, back to the monitor in sleep mode and fans blowing at 100%. It stays that way till i flip the power supply switch in the back (holding the power button does not do anything).

A friend of mine suggested the temperature sensors are off somehow and the system thinks its overheating as its booting up or down. I've also been told the power supply might have a problem. I was hoping in buying the AX series power supply i was buying one of the best available and the same goes with the sabertooth p67. The system is roughly a year old. As I can actually use the computer its not a real emergency, however all these hard boots make a bit nervous about the systems longevity.

Anyways here are the stats, I will be most gracious for any help.

-Corsair Carbide 400R
-Corsair AX750
-ASUS P67 Sabertooth
-SB 2500k
-Corsair H60
-8GB Corsair Dominator 1600mhz
-Corsair Force Series GT 120 GB
-Western Digital 1 GB Caviar Green
-2x MSI Twin Frozr 6950 2GB
-Windows 7 Professional
-No optical drive (use external if needed)
-Dell U3011 (not that it should matter)

I hope I have not left out any pertinent details, but will provide anything that might help if asked for.

Again thanks in advance.

 

[Puppies04]

Can you confirm all the fans spin up when the pc should be off (does this include the cpu cooler) and also are the case fans plugged directly into the mobo or psu or a fan controller.

 

[paul878]

Try unplug the power button connector and short the jumper to power on/off.
Re-seat all the power connectors on the motherboard.

 

[Don Blake]

I have the same problem with my Dell studioXPS920 running Win7Pro 12 GBsRAM 1TB HD 1GB ATI VC (Bought late 2009) When left overnight shut off it'd start acting up upon start-up next reboot. When button pressed on PC all fans running, Dell LED logo on tower lites up but not the orange LED startup button. PC humming cheerfully yet no video on screen or boot up sound. When I try to shut off using PC button it won't shut off only shuts off from the power bar switch then to restart after pressing the PC button it'd lite up orange this time and it'll start normally when I need to shut off the nightmare begins again.

 

[bookwormsy]

Swap in another PSU, and see if you still have a problem. If you don't, see if you can RMA the PSU. If not, buy a new one. Using a faulty PSU can't be good for your components.

 

[copeman]

possibly the BIOS acting up? Any new firmware out there for the MB?

 

[Don Blake]

Is there any other way besides updating the BIOS? I don't wanna tinker with it if possible that other avenues available. For now at night when I shut off it's OK shutting down normally. But if I have to start again I have to shut the switch at the power bar then turn it back on again it is as if needed a fresh juice to push it to start. Once started everything is fine ????

 

[Vaz]

I'm positive you have hardware damage. I don't know which but the mainboard or the power supply is at fault. There is something that regulates the flow of power into the board and components which seems to be the malfunction. my guess is the device is part of the board. You have to test these two to see which is at fault. Hook up your psu to another computer or put another unit in your computer, then tell us the result,