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  Computer Won't Start, Won't Stop, But Works Fine 
 
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PeteC Nov 29, 2011, 09:55am EST Reply - Quote - Report Abuse
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Yep, works fine but takes some technique to start and stop.
I am sure this is a hardware problem and I need to understand more about how typical power supplies work. Here is the problem:

When the computer is on and running fine, I shutdown, either using the "Start" button or a quick push of the power button. The computer goes through all its shutdown steps until everything goes dark and just when I would normally hear everything stop, it starts to reboot again.
I have experimented and found two different things I can do at that point.

(1) Hold down the power button for 6 seconds. It will then power down properly.

(2) Pull the plug. So that stops it also. Duh!

Now, to restart later:

If I did #1 above, pushing the power button will NOT start the computer no matter how much I try. I have found that there is an LED on the mother board that is always on. If I unplug the computer and wait untill the LED goes out (about 6 seconds until the caps discharge) then plug it back in and push the power button it will boot normally.

If I did #2 above, I am sitting with the computer unplugged so I plug it back in and it reboots all by itself; no push of the power button or anything. This happens even many days later. I have disabled all the ethernet power-ups etc in the bios. Which is consistant with it not starting in case #1 even if power has been always on.

I have gone through all the software checks I can find on the net. I have concluded that the power supply logic is messed up. Does anybody know why, in case #1, I should have to unplug it until the LED goes out? What does the LED "say"?

What state can the power logic be in such that it turns on just because the power is reapplied, even days later?

Thanks In Advance,

Pete


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john albrich Nov 29, 2011, 10:43am EST Reply - Quote - Report Abuse
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Edited: Nov 29, 2011, 10:48am EST

 
>> Re: Computer Won't Start, Won't Stop, But Works Fine
PeteC said:
...If I did #2 above, I am sitting with the computer unplugged so I plug it back in and it reboots all by itself; no push of the power button or anything. This happens even many days later. I have disabled all the ethernet power-ups etc in the bios. Which is consistant with it not starting in case #1 even if power has been always on....


A few things:

1) might try unplugging the front panel switch from the mobo header and see if the symptom of rebooting you mentioned continues (e.g. no possible problem due to defective front panel switch/cable subassembly). Although this should require a transition in logic state from the front-panel button to do anything, it's also possible that a hardware problem on the mobo is causing false operation of the power-on/off subsystem (e.g. if there's a lot of ripple or "noise" on the +5V line, or defect with the pull-up resistor, etc.)

2) Ethernet isn't the only option that interacts with system "wake-up" protocols. Try looking for all wake-up enables, and turn off ALL power management, including any "Green" power management drivers. The ACPI has been squirrely ever since it was first introduced, and some motherboards just have trouble handling it properly. Also, if you have Windows/system options such as "hibernate" or "sleep" enabled, disable them and see if there's any difference.

3) Try clearing the CMOS memory and using system defaults. Then (if problem "went-away") progressively add-in your preferred settings until it appears again (a corrupted CMOS can cause highly unpredictable behavior and a simple checksum may not detect that it has been corrupted). Also, until problem solved, don't re-enable any overclocking, overvoltage, etc settings that you've applied if any.

PeteC Nov 30, 2011, 11:47am EST Reply - Quote - Report Abuse
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>> Re: Computer Won't Start, Won't Stop, But Works Fine
John,

Thanks.

> 1) might try unplugging the front panel

I pushed the button to start it the unplugged at the mobo side. Next powerdown (via windows startmenu) and it restarted like always. Good idea though.



>2) Ethernet isn't the only option that interacts with system

I had disabled all I could find in the cmos and did the defaults. No overclocking. This is an old Dell system that I keep alive for legacy reasons. I have old parallel port prom programmers and processor programmers that I need to use every now and then. They are not connected now.


When I powered down this time I had to unplug it to make it stop. That was last night. I plugged it back in and it rebooted. Front panel still unplugged. I'll see what it does after being unplugged overnight and report back

Thanks again

Pete


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