Rebooting your computer is the most common first-step remedy for most PC ailments. Rebooting returns all of your computer’s software (and hardware) to a known initial state, which in theory should eliminate fluctuating problems. The issue could be as simple as a software error or as complex as a motherboard or hard drive failure, but you really can’t narrow down the options until you try a few things.
Since you have to take a logical scientific approach to identify the true source of your computer’s problems, you should really eliminate all “unknowns” that could possibly exist when trying to get your computer back to a previous “known” state. For example, there could be some hardware that is “stuck” that causes a Blue Screen of Death, and it won’t fix itself until the card is powered down (i.e. a hard reboot)… all the soft reboots in the world will not fix the problem.
There’s always going to be some weird problem with your computer from time to time. Sometimes it’s a combination of hardware that just doesn’t like each other, old chipsets, immature drivers, or a bad power supply. Here are some guidelines that should help you get to the root of the problem without pulling your hair (or your PC’s parts) out.
This means turning off all peripherals that have a dedicated power source. Printers, powered USB hubs, speakers, and even external drives. It has happened on occassion that the motherboard’s BIOS wanted to boot from an external drive that didn’t have any boot information. It’s also possible that an external device can’t initialize, which could cause a hang, BSOD or other error.
This doesn’t mean sleep mode or a soft reboot. Your computer should be completely dead to make sure there aren’t any lingering problems. Most computers today have an ATX power supply, which means that there’s a little trickle of electricity to your motherboard so it can detect when the power button is pressed. Some motherboards even have an LED on them to let you know that the motherboard is receiving some power.
The only way to make sure there is ZERO power going to your computer is to unplug the power cord… Don’t just unplug the cord from the wall, unplug it at the power supply. In a fit of panic you may forget that you have a UPS powerstrip, so unplugging the cord from the wall just trips the UPS’s battery on.
You may have to wait a few seconds before power is completely exhausted. You may have heard the tech support guy from India state that “you need to wait 30 seconds before you turn your computer on”, and there is some truth to this. The large capacitors inside your PC’s power supply store electricity (which is why it’s dangerous to touch them even when the power is off), and they can take some time to discharge. Thirty seconds may be a little excessive, though… my motherboard’s LED usually goes out within 5 seconds.
Make sure you unplug all cords for all external devices. Just to be safe, only have your PC and monitor plugged in if you find yourself in this hardcore “elimination” mode.