Random reboot with no warning. HELP!

[jollyjohn]

Hello everyone.

Home built. Windows 7 Ultimate 64 BIT. Asus P5G41C-M LX, Intel Pentium(R) Dual-Core CPU E6500 @ 2.93GHz, RAM: 8GB. G Skill F3-17000CL11-4GBXL DDR3-SDRAM PC3-12800 (800 MHz) - [DDR3-1600]
Format : UDIMM (133.35 x 15) Size : 4096 MB (2 ranks, 8 banks) (2modules).

It started doing it rarely and progressed to sometimes go into a booting loop. Tho only way I can stop it from doing it is to unplug the PC from the wall socket, earth the prongs on the plug and tap the start switch many times. I don't know for how long that'll work.

Memory is good, scanned with various antivirus and anti malware, did a system restore with the install disk and the console replacing the back up system files and folders in the config folder: RegBack, DEFAULT, SAM, SECURITY, SOFTWARE, SYSTEM. As a last desperate resort, last night, reinstalled a backup image of the HDD from last November. It did nothing, still rebooting unless I unplug from the wall socket, then it works for hours till I turn it off.

I have not tried the bios nor checked for damaged capacitors on the MB or the G card.

Please help me. Any suggestions I will try. I have searched on Google but nothing works.

John

[hello_hello]

I'd start by disabling automatic restart.
http://pcsupport.about.com/od/windows7/ht/automatic-restart-windows-7.htm

You could also try looking for previous BSOD logs.
http://www.howtogeek.com/163452/everything-you-need-to-know-about-the-blue-screen-of-death/

When it's in a reboot loop does Windows load, or does the BIOS keep trying to boot? If it's the latter, it's probably hardware. I had a faulty DVD drive at one stage that'd cause the PC to lock up or blue screen. It drove me nutty until I worked out what it was. I hadn't been using the DVD drive, but it was obviously faulty. It could be a dying hard drive. The BSOD messages may point you in the right direction, although they're pretty cryptic and it's not always easy to work out what's causing them.

If Windows loads during the reboot loop, try starting it in safe mode to see what happens. http://windows.microsoft.com/en-au/windows/start-computer-safe-mode#start-computer-saf...mode=windows-7
It'd probably also pay to go into the BIOS and load the defaults.

[redwudz]

What hello_hello said, then also unplug all but the boot drive and all cards except the video card.
Reseat the video card. (Remove and replug), and do the same with the RAM and all cables.

Run a voltage monitor program like [HWmonitor] to check voltages, etc.

If the software checks out, then it's likely the hardware.
Lastly, it could be a failing power supply, but substitution is the easiest way to check.

EDIT: I meant to link to HWINFO. I have found HWmonitor to be unreliable for voltage readings.
http://www.hwinfo.com/download.php

[DB83]

No expert here but your comment about un-plugging from the wall socket and then it runs ok could be the clue. Some issue between the mains lead and the power-supply.

[Bjs]

Replace power lead ... sometime they fail

As for reboot and loops if that doesn't fix it try a bootable linux distro and see if it runs and stays stable ... I suggest puppy linux (gui interface) ... then you can dig a bit deeper into the problem.

[hello_hello]

Can you end the reboot loop by simply pressing the power button and holding it down for a few seconds? That should turn the computer off.

[jollyjohn]

I'd start by disabling automatic restart.

If Windows loads during the reboot loop, try starting it in safe mode to see what happens. http://windows.microsoft.com/en-au/windows/start-computer-safe-mode#start-computer-saf...mode=windows-7

Auto Restart was disable.
Windows loads fine but it could be a minute later that reboots. It stays solid on safe mode.

What hello_hello said, then also unplug all but the boot drive and all cards except the video card.
Reseat the video card. (Remove and replug), and do the same with the RAM and all cables.

Run a voltage monitor program like http://www.cpuid.com/softwares/hwmonitor.html to check voltages, etc.

If the software checks out, then it's likely the hardware.
Lastly, it could be a failing power supply, but substitution is the easiest way to check.

I'll open the box tomorrow and disconnect components and clean connections and slots.

Yes. the PC stops when I press the start button for a few seconds, but if I don't unplug from the wall it reboots again.

What gives me the sh!ts is if I unplug the PC It works fine all day all night.

There are no blue screens.

Thank you all for your input.

John

[KarMa]

I recently had similar problems to you, basically my computer would lock for some reason usually having to do with opening a program or scanning the hash of a file or a few other things. It also had a bad habit of crashing when I was away from it for many hours and over night. I eventually came to the conclusion that I had an undersized PSU. Over the years I have added 3 PCI cards, gone through 2 CPUs, doubled RAM, new mobo, 3 spinning HDDs, but I still used the same PSU. Anyway I guess it could not keep up with the demand and so started stalling out the computer. I got a higher wattage PSU and nothing has really happened since, it was like night and day.

Update: You picture shows your 12V voltage at around 7V. Usually mobo voltage sensors aren't the greatest but that looks really low/bad.

[aedipuss]

your power supply is failing badly. the 12 volt reading is only 7.7 volts. time for a new one.

[DB83]

Do those same reports when the PC? is un-plugged from the wall socket.

That alone tells me (and probably everyone else) that you have a battery-powered laptop here. And, yes, the 12 volt rail of the PSU can not survive on 8 volts. But if it shows 12 volts+ when working alone there is an issue at the mains end.

Did you consider that the mains socket itself could be the villain ?

[redwudz]

I would double check the voltage on the 12 VDC rail in BIOS. Not all aftermarket voltage monitor programs give correct readings.
I mistakenly suggested HWmonitor earllier, which I don't trust any more.
It also told me I had 8 VDC on the 12 VDC rail on a perfectly working PC.

I use HWInfo now: http://www.hwinfo.com/download.php

I doubt the PC would run with 7-8 VDC on the 12 VDC rail. But there may still be power supply problems.

The OP says he has a ASUS P5G41C-M LX Micro ATX motherboard.

[DB83]

^^ Ok. I just re-read the OP.

But if he has a desktop how the $£^& can that run without being plugged in to the mains ? Or did I just read that line wrong.

[aedipuss]

^^ Ok. I just re-read the OP.

But if he has a desktop how the $£^& can that run without being plugged in to the mains ? Or did I just read that line wrong.

LOL not even his little microATX motherboard would fit in a laptop. it was strangely worded

[jollyjohn]

I would double check the voltage on the 12 VDC rail in BIOS. Not all aftermarket voltage monitor programs give correct readings.
I mistakenly suggested HWmonitor earllier, which I don't trust any more.
It also told me I had 8 VDC on the 12 VDC rail on a perfectly working PC.

I use HWInfo now: http://www.hwinfo.com/download.php

I doubt the PC would run with 7-8 VDC on the 12 VDC rail. But there may still be power supply problems.

The OP says he has a ASUS P5G41C-M LX Micro ATX motherboard.

New picture

[johns0]

Sounds like its either bad ram(incompatible) or a conflict in your system device drivers.Also a failing motherboard could cause the issues and be kinda fixed with the board voltage being completely dumped.

[turk690]

I have not tried the bios nor checked for damaged capacitors on the MB or the G card.

I would do that now. I'll also open up PSU if I'm up to it and see the capacitors there also (or go ahead and buy a new 600W one...) In addition, I'll take the CMOS battery out (to fully reset BIOS values to default) and measure it. Anything below +2.8V is bad; new ones are +3V. Pentium dual-cores are improved versions of Pentium Ds which were wont to really get hot. Just the same I'd remove the CPU heatsink-fan assembly completely, remove as much dust and dirt as possible, clean CPU and heatsink with alcohol, reapply fresh thermal paste, then put back. Use an app like Core Temp then run Prime95 to simulate 100% CPU cycles and see if it still reboots galore.

[Nelson37]

Boot into the BIOS or CMOS setup, then let it sit overnight or longer. This will completely eliminate Windows or any other software from the equation. If it reboots in this state, you have a hardware problem or mains power issue. It is also obvious as the screen will change.

If you do not already have a battery-backup surge protector unit, GET ONE. I strongly recommend APC units. Flaky power can cause such problems, and also damage components permanently, which can also cause similar problems. This has totally eliminated many such problems for many dozens of my customers, over more than two decades. I consider a good unit of this type MANDATORY. Using the battery backup feature will almost completely eliminate any mains power issues from contention. Poor building ground can remain as a possibility. DO NOT IGNORE THIS! I have personally witnessed poor building ground cause this exact type of problem, through MULTiPLE types and combinations of backup/surge/line conditioning equipment. Exceptionally simple fix for an electrician.

Check CPU and chipset temps with software, finger, and digital thermometer. Use at least two methods.

After combining the above two, if it still fails, then it is a simple process of eliminating components by simply disconnecting them, most likely will come down to mobo or power supply. If no failure, IMO unlikely, then use the selective start feature in safe mode to disable startup sections, then narrow it down to individual prog.

In the last week to 10 days, what is the LONGEST time the PC has run correctly, without rebooting? This information is vitally important for designing the testing procedure. Make a change, as described, then observe the PC for at least twice, and preferably three times, as long as the current longest observed non-failure run-time. Random chance must be eliminated or you end up chasing your tail.

[jollyjohn]

Turk and Nelson, Thank you for your help and advise.

I have been working on the PC, in between doctors appointments, for the last three days. I disassembled it completely including the PSU. There was so much dust and lint inside, both, the PC and the PSU. The heatsink on the CPU was clogged with dirt as well as the fans. There were no bad caps nor dry solders. I vacuumed and brushed the dirt, cleaned the RAM and G card slots and the gold plated contacts on card and RAM modules. Cleared the CMOS on the jumper and changed BIOS battery. The PSU testes good on all voltages, about 5% above.

I'm happy to say, the PC started OK when tested with only the OS HDD, mouse, keyboard and monitor. I turned it off and on, a few tims, let it run for some time, did that for a few hours and never rebooted on its own. I reconnected the data HDDs and the modem. I did not installed the optical drive, listening to hello_hello, in his post. I also changed the power cord.

Nelson, thank you for your post. I have printed your it and I'm going to keep it handy to follow your advise in case it happens again. I'm still doing the test you suggested. So far so good, but it is to early to start counting the chicken.

Kind Regards

John