Trouble-Shooting Your Build (Part 2) - Unexpected shutdown, Unexpected reboot

5/19/2012 9:21:07 AM

Incompatibilities during the build

Although most combinations of PC components slot together seamlessly, sometimes you’ll find a particular component that just won’t play ball. A very common problem is where motherboard and case designers clash in their decision on how many pins to make the power LED connector. On most motherboards this is a three-pin-wide header with a bank slot in the middle. In other motherboards, the blank pin is omitted and a two-pin design is utilised instead, as with the HDD-activity LED. Fortunately, modifying a three-pin header into a two-pin one is simple, and it can be done with a hobby knife or simply using a precision flat-head screwdriver to lift the plastic pin cover, remove the female metal section of the pin and install it in the adjacent blank hole. It’s annoying that a problem we were dealing with 15 years ago is still prevalent in 2012, but that’s just part of being a PC owner!

Description: PC components

PC components

Another very common hurdle people have to overcome is an inability to get the add-in cards (graphics and PCI cars) to properly seat in the relevant slots. In a perfect world, all motherboards, cases and standoffs would be precision engineered to fractions of a millimetre. In the real world, unfortunately, this is not the case, and it’s not uncommon to have problem sliding the PCI backing plates into the relevant long rectangular holes in the case. This is fortunately easy to remedy and just requires bending of the PCI backing plates very gently either towards or to the back of the card until it slots in.

Problem during OS installation

Description: During driver installation the Windows operating system

If your PC fails with a blue screen error during the installation of Windows, there can (as usual) be a number of potential things that have gone awry. One of the most common is that you have a problem with your memory configuration. It may need more voltage, less voltage or may need to be run at more relaxed latency timings. Go into the BIOS, set your memory to the failsafe slowest speed and manually force the latencies to 9-9-9-24 timings for DDR3. If this does not resolve your issue, use a different PC to create a memtest 86+ boot CD ( and see if it throws up any errors. If the memory is error free, the cause may be as a result of something else, like a hardware incompatibility, faulty motherboard or overheating CPU.

During installation of the OS, at some point the operating system looks for hard disks and may throw up a message saying it cannot find any. This is normally caused by the fact that the chipset or controller you’re using requires drivers that are not natively known by Windows. This problem is a lot less prevalent with Windows 7 than it was in Windows XP, but some of the latest hardware may require a third-party driver, which can be loaded from a pen drive or DVD.

Unexpected shutdown

Description: Error notification

Error notification

If everything seems to be running smoothly, but then your system suddenly shuts down or reboots unexpectedly, then you have a problem. It’s important to determine which of these two things is actually happening, because a system turning itself off completely is invariably more serious than one that occasionally reboots itself. The most common cause of the former is overheating. Modern chips don’t struggle on regardless once they get hot. Instead, they reduce the clock speed down to a safe speed to maximise the time before which temperatures get out of control. This is commonly known as throttling and serves to minimise CPU damage caused by incorrectly seated coolers. A second level of protection that’s built into all current AMD and Intel CPUs is a thermal cut-off that will cut power to the machine once a certain temperature is reached.

If these symptoms sound familiar, check the seating of the cooler by removing it and checking the thermal paste footprint. You should be able to see remnants spread evenly across the surface of the heat spreader. If they’re concentrated only on a small section of the CPU or, even worse, are nowhere to be seen, you need to remove the cooler completely, reapply paste if necessary and reinstall the cooler carefully. Enter the BIOS and go to PC health status and watch the CPU temperatures. Most chips idle at less than 50oC. if your temperatures are significantly higher than this or continue to rise until either the reported clock speed drops or the machine hits more than 100oC and shuts off again, you know you have a cooler-mounting related issue.

Unexpected reboot

Description: A license exception has occured

A license exception has occured

If your system is plagued with the dreaded occasional instability, whereby everything seems to ben working fine but you experience the occasional blue screen error or unexpected reboot, the first stage is to try and find a way to reliably reproduce the error. After you have first successfully installed the OS, it’s always prudent to run a soak test before you start using the machine. One of the best tests for CPU and memory is Prime 95, a program that can be grabbed for free at Within the Torture test menu you will find several options. ‘Blend’ mode is ideal for stressing memory while ‘Small FTTS’ is better for generating the maximum load on your CPU. The test will run perpetually until you tell it to stop, but serious errors are normally thrown up within half an hour of testing.

Although Prime 95 cannot distinguish between CPU and memory-related problems, you can use the built-in tests modes to get a pretty good idea. If the test errors quickly in the blend test but slowly or not at all with small FTTS, you can almost certainly rule out the CPU as the root of any problems. In which case, it’s back to the BIOS so that you can adjust the memory timings, voltage or clock speed until you obtain stability. If you cannot get stability, it’s like one of your sticks is unfortunately not hitting the advertised specification or is faulty.

If your system is rock solid when it’s being used for light tasks, but seems to have problems when it’s being stressed, the most likely cause is going to be the PSU. If you’re using an underspecified PSU, it won’t be up to the job of supplying the required voltage to your processor and video card when the going gets tough. If one or more of the voltage rails dips below that required by your hardware, it will not get the juice it needs to work correctly, resulting in an error, which can emulate any other kind of instability. For this reason, instability due to an insufficient or faulty PSU can be one of the trickiest to isolate and track down.

Graphical instability, driver resets or corruption

Description: System information

If your system has noticeable graphical errors, commonly referred to as artefacts, it’s very easy to point your finger at the video card. Before you assume the worst, however, double-check that the signal cable is plugged in fully at both the monitor and the video card ends of the lead. If it’s not, you can get some very unusual behavior. If that still doesn’t resolve the issue, and you have easy access to a spare lead, it’s worth trying that as well. If your monitor has dual inputs, try it using the different interface.

If you still have visual artefacts, it’s time to do some testing. 3DMark is a great way to do this, because you can loop identical graphical tests and look for signs of artefacts. Artefacts can manifest themselves as tearing, geometry errors or speckling and are normally caused by factors including insufficient power to the video card, overheating, incompatible driver revisions or, worst of all, a faulty card.

Try running with the case side off to allow for easier heat dissipation if you suspect excessive heat is to blame. Insufficient power from your PSU can also often show up as visible errors, so if you’re concerned your PSU isn’t up to the job, there’s a good chance it isn’t. Update any driver software you installed from a provided DVD (or Windows update) to the latest from either AMD or NVidia’s site. If you cannot get stability, try a stronger PSU, or if this is unlikely to be a cause. Test the card in another PC to see if it works correctly.

If your system is using integrated graphics, then a problem that manifests as visual distortion could actually be a problem with your system memory or motherboard. Try reducing the frequency of your memory or set your motherboard to its factory defaults to see if that solves the problem.

  •  How To Overclock Your New PC
  •  How To Build Your Own PC From Scratch (Part 5)
  •  How To Build Your Own PC From Scratch (Part 4)
  •  How To Build Your Own PC From Scratch (Part 3)
  •  How To Build Your Own PC From Scratch (Part 2)
  •  How To Build Your Own PC From Scratch (Part 1)
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  •  How Not To Build A PC (Part 2)
  •  How Not To Build A PC (Part 1) - Underspecified PSU & Wrongly mounted cooler
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  •  Choosing The Right Parts For Your Build (Part 5) - Choosing your case & Picking the right storage
  •  Choosing The Right Parts For Your Build (Part 4) - Picking the right PSU
  •  Choosing The Right Parts For Your Build (Part 3) - Picking the right video card
  •  Choosing The Right Parts For Your Build (Part 2) - Choosing the right motherboard
  •  Choosing The Right Parts For Your Build (Part 1) - Picking the perfect processor
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