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[SOLVED] PC won't turn on after unplugging power cord even when computer was off.

This is a discussion on [SOLVED] PC won't turn on after unplugging power cord even when computer was off. within the Motherboards, Bios & CPU forums, part of the Tech Support Forum category. OS - windows 7 Motherboard -GIGABYTE GA-EP35-DS3L CPU - Wolfdale e8400 core 2 duo RAM - G.SKILL 4GB (2 x


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Old 03-07-2010, 10:08 PM   #1
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OS - windows 7
Motherboard -GIGABYTE GA-EP35-DS3L
CPU - Wolfdale e8400 core 2 duo
RAM - G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066
Video Card - Ati Radeon HD5850(had an hd 4850 when this started to happen)
4 harddrives

Problem:

This started happening about a year ago, I remember starting to overclock my cpu then. I suspect my previous computer setup (pentium 4), however, had the same problem because one day it refused to boot. (which was why I built a new setup)

So,
Whenever I unplug the cord from my computer (even when the computer has been turned off for a very long time), my computer will fail to turn on at all after plugging the cord back in. Absolutely nothing turns on, no light, no sounds, nada. What I do to fix it is I leave the computer unplugged, hold the power button for about a minute to discharge the residue charge in the motherboard and, while still holding the power button, plug the cord back in. It takes somewhere from 1-30 tries until my computer boots back up via this method.

It's not my power supply because I recently bought a new one and it still happens. It can't be any wiring issues because my computer turns on 100% perfect as long as I don't disconnect the power cord. This problem happens exclusively when I unplug the power cord when the computer is either on or off, or anything else that simulates that action (power outage, turning off surge protector, etc). It doesn't matter if my computer has been off for minutes or even weeks - it will fail to turn on if I unplug my cord.

In short, something is happening when I disconnect that power cord. I am thinking that my motherboard is not shutting down completely when I turn my computer off, because otherwise it shouldn't be able to tell when I'm unplugging the power cord. This leads me to think that it is either a Bios options that I changed accidentally, or a faulty CMOS battery?

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Old 03-07-2010, 11:20 PM   #2
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power supply

brand
model
wattage

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Old 03-08-2010, 12:23 AM   #3
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Just because you bought a new PSU doesn't mean the PSU is any good.
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Old 03-08-2010, 12:44 AM   #4
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the power supply is BFG Tech GS-550 550watt

http://www.newegg.com/Product/Produc...-010-_-Product

it's rated pretty well, so I figured that it would do it's job fine. =\

I'm guessing its not cmos anymore...that wouldn't make sense since cmos battery shouldn't interfere with booting up.
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Old 03-08-2010, 12:57 AM   #5
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I suggest you need to get a higher wattage PSU.

The 5850 requires and minimum of 500w to run then you need to take into account the cpu,motherboard,ram,hard drive, opticle drive, fans etc etc

The cpu alone will use 75w along with the motherboard. I suggest looking at a better make of psu too such as the corsair 650TX
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Old 03-08-2010, 01:34 AM   #6
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I think the minimum of 500 watts rating accounts for the cpu, motherboard, ram, etc. In benchmarks, the hd 5850 loads around the low 200 watt area. I'm not sure if the evidence really suggest a insufficient psu since I regularly play graphical intensive games for hours at a time (bad company 2, mass effect 2, etc) without any history of freezing, artifacting or crashing. If anything, i should be experiencing crashes instead of boot up failures.

Plus, my computer boots up perfectly fine as long as my power line is never interrupted. It is ONLY when I unplug my cord when bootup fails.
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Old 03-08-2010, 01:46 AM   #7
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no the wattage just accounts for the card itself not the cpu etc.

I have been building systems for years and used to test power supplies for a living so I know how they work.

when it says it needs 500w this is what it needs for full load without the motherboard, cpu and anything else.

however some systems whilst underpowered will seem to work ok for a long time then the user will start to experience problems before a catastrophic failure happens.

Why do you keep unpluggin the power cord?
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Old 03-08-2010, 02:04 AM   #8
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I unplug them when I move around my computer ie. to connect to the TV downstairs, or move it between my dorm and my parents house.

It may be the psu problem.. but how does that account for boot failure when I unplug?
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Old 03-08-2010, 02:07 AM   #9
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do you switch the psu off before unplugging the cord? if you don't then you are unintentionally causing the psu to spike the motherboard.
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Old 03-08-2010, 02:10 AM   #10
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Actually, if I switch off the psu and then switch it back on, the boot failure still happens. Anything that simulates power being disconnected causes the boot failure, so pulling the power cord, switching off the psu, power outage, etc. It's strange, if my computer is turned off, then why it "recognize" the line being cut?
But now that you mention it, I usually pull the plug without switching off the psu, maybe that is damaging the motherboard in a way that causes my problem?

Anyway, I changed the A/C Power Loss Restart setting in my bios from disabled to always on. I'll have to wait till break to test it since I need my computer working for work.

I'm soon to be upgrading to an i7 860, so I'll see if the same problem occurs with that setup. I'm going to send my old parts to my friend, and I certainly wish for the problem to be fixed before giving that to him.
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Old 03-08-2010, 02:18 AM   #11
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a computer is always on even when you have it switched off. The only time is when it completly dead is when the psu has been unplugged and switched off for several hours (sometimes days).

A psu that has been unplugged and turned of for 3 days can still output enough voltage to give you an electric shock that is enough to kill you, so in that essence it can still supply power to the motherboard.
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Old 03-18-2010, 03:04 PM   #12
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Sorry for bumping an old thread, but the problem is solved, and I thought that the information may be helpful to other people. The problem was that my A/C power loss restart option in bios was set to disabled. I set it to enabled, and now my computer boots perfectly no matter how I tinker with the power.
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Old 03-19-2010, 12:52 AM   #13
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thanks for posting your solution

glad you have it sorted

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