Windows 7: Intermittent power off

Over the past 2 years my PC has been afflicted with random power off/power on/reboot events. It will go for months without these and then have multiples of the events in a day. (I had 8 of them 3 days ago.) I assume I have a hardware problem, but nothing has been found and I'm grasping at straws.

The time between power off and power on is several seconds. I had assumed this rules out a software cause, but maybe I'm wrong. I know Windows can schedule a power off, but can it tell BIOS (or something) to power back on in a few seconds? And would it do this for any kind of problem?



I know blaming the power supply is a much more simple explanation, but then I'm left with explaining the intermittent nature of the failure.

Please provide us with your Event Viewer administrative logs by following these steps:


Click Start Menu
Type eventvwr into Search programs and files (do not hit enter)
Right click eventvwr.exe and click Run as administrator
Expand Custom Views
Click Administrative Events
Right click Administrative Events
Save all Events in Custom View As...
Save them in a folder where you will remember which folder and save as Errors.evtx
Go to where you saved Errors.evtx
Right click Errors.evtx -> send to -> compressed (zipped) folder
Upload the .zip file here.

There's a lot more in the attached file than you need - it goes back to last October. As near as I can tell, no records get written for these failures. You can tell one has happened because there is Event Log event 6008 and/or a Kernal-Power event 41 logged on restart. (I have no idea why I don't always get both.)

Nothing in your error logs to indicate the cause of your crashes. Run some hardware tests:

•    Warning

  Before you proceed with the following, answer these two questions: Are you still under warranty? Does your warranty allow you to open up the machine to check hardware? If you are unsure of the answers to these questions, contact your system manufacturer. WARNING: The steps that follow can void your warranty!!!
  
  Monitor temperatures during the following tests.

  Use the following programs to monitor the temperatures.

  • Real Temp is a good CPU temperature monitor.
  • Speccy - System Information - Free Download will monitor all hardware temperatures.
  • HWiNFO, HWiNFO32 & HWiNFO64 - Hardware Information and Analysis Tools can be inaccurate for CPU temperatures, but is a good program for GPU temperature monitoring.

  • Use FurMark: VGA Stress Test, Graphics Card and GPU Stability Test, Burn-in Test, OpenGL Benchmark and GPU Temperature | oZone3D.Net to test the graphics card GPU. Let it run until the GPU temperatures even out or until the GPU temperatures reach a dangerous level (you can find the max temperature for your card on either the nVidia or AMD sites; if you are not sure, ask us). The goal is to get a steady temperature, find out if the GPU is overheating, or to see if there are any artifacts present in the test itself: look for strange pixelated patterns on the screen or colors that do not look like they belong. Then use the |MG| Video Memory Stress Test 1.7.116 Download to test your graphics card memory. Let the memory test run for at least seven passes; the more the better.
    
    
  • Run Hardware - Stress Test With Prime95 to determine any hardware problems. Run all three tests for a few hours each. If you get errors, stop the test and post back here.
    
    
  • Follow the steps for doing CPU stress test using IntelBurnTest

•    Warning

  Before you proceed with the following, answer these two questions: Are you still under warranty? Does your warranty allow you to open up the machine to check hardware? If you are unsure of the answers to these questions, contact your system manufacturer. WARNING: The steps that follow can void your warranty!!!
  
  Run the boot version of Memtest86+ paying close attention to Parts 2 and 3 of the tutorial. Also, in case Memtest86+ misses anything and comes up with no errors, run the extended version of the Windows Memory Diagnostics Tool for at least five passes. These you may want to run overnight since they take a long time to complete (run them an hour before bed each of the next two nights and check before going to sleep that they are still running).
  
  For Part 3: If You Have Errors: If you swap any memory components, follow these steps for ESD safety:
  1. Shut down and turn off your computer.
  2. Unplug all power supplies to the computer (AC Power then battery for laptops, AC power for desktops)
  3. Hold down the power button for 30 seconds to close the circuit and ensure all power drains from components.
  4. Make sure you are grounded by using proper grounding techniques, i.e. work on an anti-static workbench, anti-static desk, or an anti-static pad. Hold something metallic while touching it to the anti-static surface, or use an anti-static wristband to attach to the anti-static material while working. If you do not have an anti-static workbench, desk, or pad, you can use your computer tower/case by finding a metal hold in it, such as a drive bay.
  Once these steps have been followed, it is safe to remove and replace components within your computer.

I've run Furmark until the temperature stabilized - about 20 minutes - and Prime95 for about 30 minutes. I guess I'll give them longer runs but I'm not expecting much since I never really stress my PC (except for running those tests), and sometimes the crash happens within a few minutes of powering on the PC - definitely not a period of stress. (And yes, I know that marginal hardware that fails a stress test can fail at other times, too. I'm just not very hopeful that the CPU and GPU are the culprits.)

I've twice failed to create bootable CDs for Memtest86+. Probably a dumb user error. I've run the Windows Memory Diagnostics tool several times but only for 2 passes. No problem was found.

Question about my PC's behavior during failure. It seems to do a full power off followed a few seconds later by a power on. I've been told that there probably would not be an automatic power on for a failing PSU. What kind of failure would prompt an automatic power on? Or am I wrong thinking there is a power off? (I'm not sure how I'd know other than looking at the "pilot" light and listening for the fans, drives, etc.)

BTW, my PC seems to have entered one of it's well behaved periods. No failure for a week or so.

It is likely the computer is restarting and not actually shutting down. However, given your description, I do not want to rule out abnormal behavior.

Clear the CMOS: How To Clear CMOS (Reset BIOS)

Reset BIOS hardware/software connections and clear any corruption of your temporary memory:

1. Shut down and turn off the computer.
   
2. Unplug the computer from the wall or surge protector (then remove the battery if it is a laptop).
   
3. "Remove the computer from any port replicator or docking station, disconnect
   cables to printers or devices such as external monitors, USB memory sticks or SD cards, headset or external speakers, mouse or auxiliary keyboard, turn off WIFI and Bluetooth wireless devices." (Use Hard Reset to Resolve Hardware and Software Issues HP Pavilion dv5000 Notebook PC series - HP Customer Care (United States - English))
   
4. Hold down the power button for 30 seconds. This closes the circuit and ensures all
   power from components is drained to clear the software connections between the BIOS
   and hardware and clear any corruption in the temporary memory.
   
5. (If it is a laptop, plug the battery back into the laptop and then) Plug the computer back into the wall. Do not reconnect any unnecessary peripherals; monitor, keyboard,
   and mouse should suffice and be the only peripherals reconnected.
   
6. Turn it on to reinitialize the software connections between the BIOS and hardware
   

I agree with writh that you are probably blue screening with automatic restarting option on. Go into control panel, system, advanced, startup and recovery, and turn off "automatically restart" ..

Also, if you really are FULLY shutting down, and starting back up... then this is a feature in the BIOS power management. Look for "automatically power on after power failure" or something similar.

No, I definitely don't have automatic restart specified. That was one of the first things I changed when this started happening. In fact I don't get a BSOD at all - just a sudden thump in the speakers, a black monitor, and silence from the box. Then about 5-10 seconds later it's as though I'd just powered up.

I will look for a power option in BIOS.

What temperatures are you getting at idle (leave the computer be for 10-15 minutes with no applications running and check the temperatures; you may need to turn off power management settings so it does not sleep or hibernate)?


What temperatures did the GPU and CPU level off to during stress tests?

I didn't save the results of the tests - just noted that I didn't get a failure. I'll run the tests again later on and post the results. I'm using HWiNFO64 and CPUID HWMonitor to monitor the temperature; I don't have Speccy.