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HELP!!! Computer won't boot up after power outage

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October 6, 2010 4:24:14 PM

After electrical power outage, my computer won't boot up.

Here are the symptoms I have noticed.

1) When I power on, all the components including motherboard, graphic cards, hard-drive, CD-ROM, and fans get the power.

2) Monitor screen displays this message "No Signal", and does not display anything else.

3) I cannot get to the BIOS screen


Here are some things I have done to fix the problem.

1) Unplug all the cables and perform hard reset on the computer. I've also waited few hours before plugging back the cables.

2) Replaced graphic card with different one (graphic card test)

3) Removed 3 RAM (3 x 2GB), and tried single RAM operation (RAM test)
~ This is to test if any of the RAM was fried. Unless all 3 RAM were fried at the same time, this test failed. How likely is it for all 3 RAM get fried?

4) Replaced existing DVI monitor cable with another.


Based on few tests I have done above, I am assuming that the component that might have fried are listed below and I do not know how to check if they are fried or not. (Please tell me if you know how)

1) CPU

2) Motherboard

3) All 3 RAM at the same time


I am about to go to MicroCenter to purchase above components, and replace each one by one, but this method is too costly just to do the testing.

I have computer project due in couple days, and I am about to cry. This is my first time dealing with this type of situation, and I would appreciate if any of you could give me your wisdom to resolve this issue.

FYI, components that I am using are listed in my signature. I built my rig about 2 months ago.

a b V Motherboard
October 6, 2010 6:04:10 PM

So you sure the PSU is ok? lol, i'm asking cause i had a user's psu go "pfft" but would still turn on the PC components. Not likely to happen, but it has =P.



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a c 111 V Motherboard
October 6, 2010 6:24:13 PM

The PSU takes AC from the wall and then converts it to DC. When too much current, such as a spike that happens after a power outtage recovery, is taken in by the PSU, it often fails to produce the AC/DC conversion correctly, thus not sending power efficiently throughout the connectors.

I suggest you pick up a multimeter and test your PSU. This should help, it is from the troubleshooting guide on this forum:

"Yellow wires should be 12 volts.
Red wires: +5 volts,
orange wires: +3.3 volts,
blue wire : -12 volts,
violet wire: 5 volts always on.
Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot."

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a b V Motherboard
October 7, 2010 2:28:59 AM

Just out of curiosity, did you have the pc plugged into a surge projector?
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October 7, 2010 2:41:17 AM

I have a feeling that he don't, if that the cases you need to buy a new PSU.
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October 7, 2010 5:18:30 AM

No no, the power supply is OK because the computer can turn on.

I'm 100% sure it's the Motherboard. I have similar experience. If the Power Supply is the cause, the computer won't turn on entirely.
If it's RAM, mostly cases the BIOS shows up, but fails at RAM test. There's 0% possibility all 3 sticks will break, meaning NEVER, at least one of the sticks will functional. Then the computer will boot, possibly entering Windows, but: RAM is not fully detected, or system instability (BSOD) but faulty at RAM will still boot into Windows most of the time (least effect on computer). If it's the processor, well the display will print mischievous symbols (like assembly codes) on screen.
It's the VGA transmission that broke. And that comes from motherboard.

But first, check out the VGA card to ensure the VGA card is still working properly.
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October 7, 2010 2:38:54 PM

andrern2000 said:
No no, the power supply is OK because the computer can turn on.

I'm 100% sure it's the Motherboard. I have similar experience. If the Power Supply is the cause, the computer won't turn on entirely.
If it's RAM, mostly cases the BIOS shows up, but fails at RAM test. There's 0% possibility all 3 sticks will break, meaning NEVER, at least one of the sticks will functional. Then the computer will boot, possibly entering Windows, but: RAM is not fully detected, or system instability (BSOD) but faulty at RAM will still boot into Windows most of the time (least effect on computer). If it's the processor, well the display will print mischievous symbols (like assembly codes) on screen.
It's the VGA transmission that broke. And that comes from motherboard.

But first, check out the VGA card to ensure the VGA card is still working properly.


That so could be the problem too.
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a b V Motherboard
October 7, 2010 2:47:35 PM

andrern2000 said:
No no, the power supply is OK because the computer can turn on.

I'm 100% sure it's the Motherboard. I have similar experience. If the Power Supply is the cause, the computer won't turn on entirely.
If it's RAM, mostly cases the BIOS shows up, but fails at RAM test. There's 0% possibility all 3 sticks will break, meaning NEVER, at least one of the sticks will functional. Then the computer will boot, possibly entering Windows, but: RAM is not fully detected, or system instability (BSOD) but faulty at RAM will still boot into Windows most of the time (least effect on computer). If it's the processor, well the display will print mischievous symbols (like assembly codes) on screen.
It's the VGA transmission that broke. And that comes from motherboard.

But first, check out the VGA card to ensure the VGA card is still working properly.


Well true. But i did have one occasion where the PSU did go bad but it would still power up the fans and led's. that was the last thing i thought it would be, but i had a spare lying around, tested it, and the PC booted up just fine.

But i think it's just one of those 1 in a 100 scenarios. Haven't had the same type of issue since then =P.
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October 7, 2010 2:59:55 PM

I recommend like stated above. Pick up a inexpensive power supply tester and make sure the PSU is working properly. As for you problem more than likely its gunna be your board by the sounds of it. If it wont post but it powers on then your PSU should be fine. your board took the brunt of the power outage/surge. Did u have it plugged into a surge protector/ backup battery source?


look on the board its self. easy way to tell if your board got fried is if the capacitors are bubbled up at the tops at all.
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a c 156 V Motherboard
October 7, 2010 3:03:01 PM

andrern2000 said:
No no, the power supply is OK because the computer can turn on.

How do you know?

Work through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...
I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

If not, continue.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different.

Breadboard - that will help isolate any kind of case problem you might have.
http://www.tomshardware.com/forum/262730-31-breadboardi...

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.

Make sure you plug the CPU power cable in. The system will not boot without it.

I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case.

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting. <==============

At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU.

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card.

Silence or long single beeps indicate a problem with the memory.

Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.

Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.

tx, the PSU testers are handy little gadgets. But the drawback is that they present a minimal load to the PSU. Therefore they give no indication if the PSU can support the full system load. They can tell you if the PSU is bad, but they cannot tell you if the PSU is good.
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a b V Motherboard
October 7, 2010 5:02:09 PM

jsc said:
How do you know?

Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting. <==============


^+1 yey! someone who knows my situation is liable to be true! xD. Awesome info btw - saving this link to my bookmarks now =)

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October 7, 2010 5:09:54 PM

Here are the updates and answers to the questions that were brought up by some of you. I still haven't fixed the problem yet.

1) I did not have surge protector at the time of incident.

2) I hear no beep sound at all when I power on my system.

3) I have tried different graphics card and PSU, and still the same.

So, I think it really comes down to two things now. CPU or Motherboard. I have talked to alot of people, and majority of them stated that the component that usually gets fried from power outage is the motherboard.

I am also personally leaning towards motherboard. I am not sure if my motherboard is supposed to display some type of error message on the screen if the CPU is fried. But if what andrern2000 wrote was true about screen displaying some other error messages or codes if it's the CPU that was fried, it must be the motherboard because it's not displaying any messages or codes generated by motherboard.

Today, I will purchase a new motherboard and see how it goes. But before I purchase a new motherboard, there is one thing I have not tried. It's the CMOS battery replacement on the motherboard. Like I said I built my rig about 2 months ago, and the motherboard and CMOS battery that I have used were brand new. Now, how likely is it that CMOS battery get fried due to power outage? I am not sure what CMOS battery does besides storing hardware information such as CPU, hard-drive, boot up, time & clock, or any other information you see in your BIOS menu. My question here is, what happens when you take out the CMOS battery from your perfectly working fine system or your CMOS battery gets damaged and you start up your system? Would it give same symptoms I have described?
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Best solution

a b V Motherboard
October 7, 2010 5:34:37 PM

Without the CMOS it would start, you just wouldn't be able to save any settings in the BIOS (like OC voltages, or RAM timings, or even the date and time) but it would post. If anything you would get a CheckSum Error.

If it was just the CMOS battery, the board would have posted, beeped, breathed life somehow by now =P
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October 7, 2010 6:02:16 PM

nexuslotus said:
Here are the updates and answers to the questions that were brought up by some of you. I still haven't fixed the problem yet.

1) I did not have surge protector at the time of incident.

2) I hear no beep sound at all when I power on my system.

3) I have tried different graphics card and PSU, and still the same.

So, I think it really comes down to two things now. CPU or Motherboard. I have talked to alot of people, and majority of them stated that the component that usually gets fried from power outage is the motherboard.

I am also personally leaning towards motherboard. I am not sure if my motherboard is supposed to display some type of error message on the screen if the CPU is fried. But if what andrern2000 wrote was true about screen displaying some other error messages or codes if it's the CPU that was fried, it must be the motherboard because it's not displaying any messages or codes generated by motherboard.

Today, I will purchase a new motherboard and see how it goes. But before I purchase a new motherboard, there is one thing I have not tried. It's the CMOS battery replacement on the motherboard. Like I said I built my rig about 2 months ago, and the motherboard and CMOS battery that I have used were brand new. Now, how likely is it that CMOS battery get fried due to power outage? I am not sure what CMOS battery does besides storing hardware information such as CPU, hard-drive, boot up, time & clock, or any other information you see in your BIOS menu. My question here is, what happens when you take out the CMOS battery from your perfectly working fine system or your CMOS battery gets damaged and you start up your system? Would it give same symptoms I have described?


As you said it could be CPU or the Mobo and please buy a surge protector so this won't happen again ok?
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October 14, 2010 12:53:33 AM

Best answer selected by nexuslotus.
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March 26, 2013 12:27:55 PM

Don't know how or why this works - but it works.... (at least it did for my mother who had the same problem)



unplug your computer
hold power button down for about 10 secs
plug the computer back in
and power up!
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