Desktop PC in reboot loop

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Jun 11, 2016
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My desktop computer rebooted itself without end. I had to pull the power cord in order to shut it down.

After consulting some friends we guessed the memory modules were the cause and I had them replaced with new ones. The abnormal behavior stopped....or so I thought.

A few days later it resumed rebooting itself numerous times. The only way to shut it down was to pull out the power cord.

I can rule out the operating system as the cause. It occurred with both Microsoft Windows and Linux OSes.

Has my motherboard been infected with some malware? (A few weeks ago my friend used his USB thumb drive to copy some files from my computer.)

Is the Intel CPU or PSU failing?

Below are my hardware specifications

about 3 years' old

Intel i5-4570 Haswell CPU
Seasonic Gold 650 watts power supply unit
Dell 24-inch Full-HD IPS monitor
D-Link ADSL2+ router, model DSL-2750E
Kingston HyperX 240GB SSD with Microsoft Windows 10 Pro
Intel 530 series 240GB SSD with Microsoft Windows 8.1 Pro

about 3 months' old

Samsung DVD rewriter (internal SATA)
Toshiba Q300 Pro 256GB SSD with Ubuntu OS
USB 2.0 external webcam

about a month old

Asus H97-Pro Gamer motherboard

about a week old

Kingston Fury memory modules (a pair of 8GB each), 16GB, DDR3 1600MHz
Aerocool tower case with two USB 2.0 and two USB 3.0 ports in the front of the case
 

pendragon1

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disconnect everything from the motherboard, remove all but one stick of ram. connect to onboard video. clear the cmos/bios by removing the power cord, remove the battery(test it while its out should be 3.2v), hit the power switch a few times to discharge the psu and let it sit for a few minute. see if that you gets anywhere. if it still happens you'll need parts to trouble shoot starting with a known good psu. good luck.
 

pendragon1

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oops! meant remove the battery then press power button a couple times. good catch! by known good I didn't mean quality I just meant another unit that you know works. just to rule it out. I'm not familiar with your psu but I think seasonic is a reputable brand.
 
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Deleted member 88227

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faulty switch on the case perhaps? Try disconnecting the case switches from the motherboard headers. Use a screw driver to power the system on by grounding the two pwr leads to one another.
 

silent-circuit

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PSU failure is unlikely since this is a boot loop, not rebooting under load or something like that. Still possible, but I wouldn't look there first. And yes, that Seasonic unit is very high quality.

No, your motherboard can't be infected with a virus, and since you say you're getting the same behavior with Windows and Linux I doubt it's a virus of any kind, just a hardware issue.

It sounds like this all started with the new motherboard. Some can be picky about RAM, it's true, but we need more information than that. Did you manually set voltage for the RAM, use an XMP profile, or just leave it at whatever the default was in BIOS? Can you get in to the BIOS at all now / is there any video output, or does it just spin fans, shut off, turn back on, etc.

Pull the CMOS battery as Pendragon said, pull the cord from the wall, hit the power button a few times to discharge everything and then leave it like that for at least 20-30 minutes. This will ensure it really resets.

As to what Skillz said above, yes, the case may be the real issue. I'd recommend pulling the board from the case entirely if a CMOS reset doesn't at least improve things. Set the board on some cardboard or something. This will eliminate the possibility of a short against the case.
 
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faulty switch on the case perhaps? Try disconnecting the case switches from the motherboard headers. Use a screw driver to power the system on by grounding the two pwr leads to one another.

I'm not brave enough to ground the two power leads to one another. Is there an alternative method?
 
D

Deleted member 88227

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Use the switch to power the computer on then remove them off the leads.

For the record; grounding those pins out wont harm anything. I normally take a philips head screw driver for most of my headless boxen and just slide it down the row until they power on.
 
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not rebooting under load or something like that.

What do you mean by the phrase "not rebooting under load"?

It sounds like this all started with the new motherboard.

Well, Asus H97-Pro Gamer is a well-regarded board that has been on the market for about 2 years now. I've googled for negative feedback on it and found none.


Some can be picky about RAM, it's true,

Quite true but Asus has a reputation of manufacturing motherboards that are compatible with most brands of RAM. Kingston has been my preferred brand in the past 25 years or so.

Did you manually set voltage for the RAM, use an XMP profile, or just leave it at whatever the default was in BIOS?

When the first series of reboots occurred, I was using Kingston HyperX Blu, DDR3, 1333MHz with overclocking capability. In the BIOS, I did use the XMP Profile to set the RAM speed to 1600MHz.

I thought the RAM was the cause of the problem and went to the Kingston service center to have them replaced. At the center the staff told me the Kingston HyperX Blu were old models and out of stock. They gave me the latest model which was Kingston Fury, DDR3, 1600MHz without overclocking capability.

In the BIOS, I disabled the XMP Profile as Kingston Fury RAM modules that I got in exchange were not overclockable.

The second series of reboots occurred two days after I inserted the memory modules into the RAM slots on the motherboard.

Can you get in to the BIOS at all now / is there any video output, or does it just spin fans, shut off, turn back on, etc.

No, there's no way for me to get into the BIOS because the time interval between reboots is very short, about 10 seconds or so.

There's no video output. The fans spin for a few seconds, the computer shuts down and turns back on again, in an endless loop.

Pull the CMOS battery as Pendragon said, pull the cord from the wall, hit the power button a few times to discharge everything and then leave it like that for at least 20-30 minutes. This will ensure it really resets.

I'll try that method.

As to what Skillz said above, yes, the case may be the real issue. I'd recommend pulling the board from the case entirely if a CMOS reset doesn't at least improve things. Set the board on some cardboard or something. This will eliminate the possibility of a short against the case.

I'm not brave enough to try out Skillz's method. I hope there's an alternative to his suggestion.

Strangely enough the reboot loop described in my original post started after I dumped my 3 year-old CoolerMaster Elite tower case and bought an Aerocool tower case, which is the one that I'm currently using. It's about 2 weeks' old now.
 
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Use the switch to power the computer on then remove them off the leads

What switch were you referring to? Sorry for asking such noobish questions.

What are "them" in your phrase "then remove them off the leads"?

For the record; grounding those pins out wont harm anything. I normally take a philips head screw driver for most of my headless boxen and just slide it down the row until they power on.

I'm keen to learn from experts like you. However a tutorial on Youtube would be most welcome :)
 

silent-circuit

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If I had to guess, based on what you're saying it could be a corrupted CMOS (in which case a reset as I described would fix it) or an intermittent short on the case. You may not feel brave enough, but if the CMOS reset doesn't fix it the next logical step is to pull the board and try to boot it caseless, sitting on a piece of cardboard or similar, to eliminate the chance of a short.

I'm keen to learn from experts like you. However a tutorial on Youtube would be most welcome :)

There's a set of wires that go to the front panel lights and switches for the case, right? Power switch, power LED, HDD activity LED, reset switch. There's a header (set of pins on the motherboard) where these all go. He's saying you should disconnect all the wires from those pins (pull the little plastic things off of them) and then use a flat-head screwdriver or a paperclip or something to touch the two pins that were connected to the case's power switch, just briefly. The motherboard sees this as a command to turn on -- it's effectively the same thing that happens when you press the case power switch, so it won't hurt anything. The reason he's saying to unhook the case switch is it may be damaged or faulty and staying closed when you press it, leading to the boot loop. This eliminates that. If it does the same thing when you use the screwdriver then the case switch is not the problem and you can reconnect it. If it works where it did not before you should test the switch with a multimeter.

EDIT: And he added a video below.
 
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Deleted member 88227

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The power switch on the case itself. Since you just mentioned you replaced the case recently I definitely suspect a short somewhere then.

Here is a Youtube video of someone using a screw driver to do exactly what I described.

 

pendragon1

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silent and skillz have said everything I would have. did you install the mobo yourself? if you did you already have enough skill to do everything needed. don't doubt yourself!
 

pippenainteasy

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Does it keep rebooting with no USB devices hooked up? Some motherboard models (mostly X99 ones IIRC) will go into infinite reboots during POST if you have any USB 3.0 devices hooked up without USB Legacy mode enabled in the BIOS. I would find a PS/2 keyboard--if you have one boot with only that installed and see if that's the issue.
 
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If I had to guess, based on what you're saying it could be a corrupted CMOS (in which case a reset as I described would fix it) or an intermittent short on the case.

Thank you for taking the time to give a rather detailed explanation to help a n00b.

Can someone explain the following cases:

1. What is meant by "CMOS corruption"? How does it happen?

2. What is meant by "intermittent short on the case"? Shouldn't it rather be a short on the motherboard?

3. How is it possible for a motherboard to be shorted by the computer case that houses it?
 

silent-circuit

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There could be a standoff installed in the case which is touching the back of the motherboard where it shouldn't, or it could be a loose screw, a wire with worn insulation... lots of things. I say a short "on the case" because the power is probably being shunted through the metal of the case.

CMOS is just an area of volatile (changeable) memory where the BIOS settings are stored - memory speed, drive boot order, voltages, CPU speed info, etc. If something interrupts power at the wrong time this can be corrupted or "scrambled." Then you need a reset.
 
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Does it keep rebooting with no USB devices hooked up? Some motherboard models (mostly X99 ones IIRC) will go into infinite reboots during POST if you have any USB 3.0 devices hooked up without USB Legacy mode enabled in the BIOS. I would find a PS/2 keyboard--if you have one boot with only that installed and see if that's the issue.

Your post just happens to jolt something in my memory.

I was using Microsoft Windows 8.1 Pro. I had hooked up a cheap USB 2.0 webcam by inserting one end of its cable into a port on the front panel of the computer case. The front of the case has 4 ports: 2 USB 2.0 and 2 USB 3.0. If I remember it correctly, I used the USB 3.0 port.

I left it on for a few hours and when I got back to the computer, I tried to shut it down the proper way via Microsoft Windows OS. That was when the reboot loop started. (The USB 2.0 webcam was still hooked up to my computer.)
 
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There could be a standoff installed in the case which is touching the back of the motherboard where it shouldn't,.....

Are the stand-offs of a universal size and length? The reason I'm asking is I might want to buy plastic stand-offs instead of the metallic ones provided by the computer case manufacturer. If I use plastic stand-offs, the chances of shorting against the case will be zero, don't you agree with me?
 
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