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Question

fans still working and led dimming after switching off PC

Apr 12, 2015 7:39AM PDT

My old pc was working fine till recently, about month ago, when i turned it off i heard a noise like it was working. The led light indicating it's ON was lightly dimmed. I opened the case and noticed all fans are working- PSU's, Graphic's, and mainboard's. I left it like that and after an hour it was still the same. From then on the pc can never shut down completely so i have to press the main power switch behind computer. I have updated BIOS to newest version, and reseted it by pulling the mainboard battery off, then restored the defaults but the problem still exists. I would be very grateful if someone would find a solution for me.
Specs:
OS- Windows XP
Mobo- ASUS p5e-vm hdmi
PSU- enlight gps-350ab c 350W
Graphics- nvidia geforce 9600 gt
Proc- Intel Core 2 Quad q6600 @ 2.4 GHz (4 CPUs)
Ram- 2048 MB
BIOS- date: 03/26/10 ver. 08.00.12

Discussion is locked

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Answer
Failures include.
Apr 12, 2015 8:30AM PDT

1. Hardware.
2. The OS hung instead of continuing to full power off.

As a test for item 2, you boot SAFE MODE and then press Start, Power off on the start menu.
Bob

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answer
Apr 12, 2015 10:18AM PDT

Thank You for quick reply, i followed Your no. 2 advice, yet the problem still exsists so it's probably hardware issue. Is there any way to check what is faulty and can i repair it by myself? Unfortunately i don't have any access to spare psu/motherboard to change it for a moment and check what is faulty.

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Of the last 10 times I had it be hardware.
Apr 12, 2015 10:26AM PDT

It was the motherboard. However since the machine worked otherwise folk usually just keep using it till it really drops dead.
Bob

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my guess is feedback from USB circuit
Apr 12, 2015 10:36AM PDT

Used to be when you turned off a computer, the motherboard was dead other than the CMOS chip supplied by the coin battery. Along came USB, and shortly after there was "always on" USB, even when the front switch had been turned off. USB is 5V power and any diode that has gone bad can allow that to bleed over into other mainboard circuits. Now, consider how many more USB circuits there are on modern motherboards. The chances of that happening increases.

You know if the back switch on the PSU turns it off completely, and the soft off on the motherboard doesn't, then the motherboard is going bad. Since USB is 5V, chances are it could run OK when fully on for awhile, other main circuits being 12V, but it still means the mobo is failing.

Plenty of info on it.

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Solution found
Apr 13, 2015 8:14AM PDT

As i eliminated software issues regarding my problem, i managed to borrow a 300 W PSU from my friend and after connecting it and plugging in the problem was gone so it was a faulty power supply in my case. Thank You guys for comprehensive help. I request for closing a thread.