So your computer won't start. We've all been there; some of us more than once. First of all, remember that your data are stored on your hard drive. Hard drives usually don't just die so it's highly likely that you can fix the offending part and turn your computer back on as if nothing happened.
That's the good news. The bad news is that the only way to debug booting issues on a desktop PC is via the process of elimination. Having to do this recently; I thought it may be helpful to share how I figure out why a computer wont boot.
But first unplug everything.
Always, Always! ALWAYS!!!!! detach your computer from the wall outlet before you open the tower.
Recently I murdered a power supply and this was my fatal mistake right here. I assumed that because I turned the switch off on the back of the power supply that I was safe. Alas this was not so. So do yourself a favor and unplug your tower.
It's also good form to unplug anything extra like speakers, monitor, mouse / keyboard. The less variables you have to deal with the better.
And be careful, static will kill
Have you ever touched a doorknob and got a little zap. Did you know that little static charge is enough to kill the circuits in your mother board? If your going to do anything more than add RAM to your computer, and we are, then I strongly suggest an anti-static wrist guard. It goes on your wrist and is clipped to something metal, usually the tower, to keep you grounded.
Now it is true that when the motherboard is inside of the tower it's basically grounded by the metal case. This is why towers are metal and not plastic. However do you want to pay $5 for a wrist band or do you want to go through what I just dealt with because your cat rubbed up against your leg while you were touching the processor? Your choice.
#1. Check for an easy short
If a screw comes loose and is rolling around in your tower it could come into connection with your motherboard, create a circuit and short it out. Don't shake, but gently tilt your tower from side to side listening for a loose screw. If nothing open it up and look for obvious cords laying across the board. If you don't see anything head to step 4.
#2. Out with the new in with the old
If you've just added something, remove it. Maybe you just added a defective part, or maybe the part you just added requires a larger power supply than you currently have.
Which brings me to...
#3. Is your power supply enough? And does it work?
If your supply is on the low side, less than 450-500 W you may have too much hardware and not enough power. If you've just added something, or built your system, double-check the wattage of your motherboard, graphics card, RAM(s), and fans and make sure your not over your power supply.
Just to give you an idea, the computer I built has 4 fans, an overclocked Intel quad core i5 processor, and a "superclocked" EVGA GeForce GTX 660 graphics card and I put a 750W power supply in it. When I tried to test just the motherboard and processor with a 450W and it wouldn't even turn it on.
Besides not having enough juice the power supply is the number one thing to break on a desktop PC. Why you ask? Well it's because it's the barrier between your outlet and your motherboard. So if lightning strikes and no ones around to hear it, it may not make a sound but it can certainly blow the power supply.
So to save yourself the heartache of replacing the wrong part get a multimeter and test your power supply. Or in the very least take your computer somewhere and have it tested before you buy new parts. Trust me you don't want to end up with an extra opened motherboard that you can't send back.....
Here's a YouTube video on how to use a multimeter to check your power supply.
#4. As you unplug parts check the connectors
Step 5 involves unplugging all unnecessary hardware from the motherboard. As you do that look at each cable and plug to see if any pins are damaged. If they are replace the cable or remove that piece of hardware and try your computer again.
#5. Remove everything that the computer doesn't need to run
Remember to power off and unplug your tower before adding or removing any hardware.
Unplug the hard drive (you don't have to remove it from the case just unplug from the motherboard AND power supply), optical drives, RAM, fans and remove the upgraded graphics card if your computer has one. This leaves you with a motherboard and CPU hooked to your power supply.
What were trying to get from doing this is a POST beep. To hear the beep need a speaker hooked up to the motherboard. Ideally you should use an internal mini on board speaker that connects to the motherboard circuit breaker. One should come with a motherboard if you built your computer.
If you don't have a mini speaker then hook up the Audio connector to your tower and connect an external speaker. It is very important that your sure the speaker works before you rely on the post beep for debugging.
Hit the power button or manually trip the power circuit to start your computer. If you hear the beep you know that your mother board is alive and receiving power.
Whats a post beep?
Have you ever clicked the power on a computer and heard a mechanical "BEEP" and then the operating system starts to load up on the screen? This is a POST (or Power On Self Test) beep and that one beep means the system is normal.
POST beeps are similar to Morse Code as in they're trying to convey a message. Here's a general chart of what the different patterns may mean.
- Steady or short beeps,
- Power supply may be bad.
- Long continuous beep tone,
- Memory failure.
- long beeps Power supply bad.
- No beep,
- Power supply bad, system not plugged in, or power not turned on.
- If everything seems to be functioning correctly there may be a problem with the 'beeper' itself. The system will normally beep one short beep.
- One long and two short beeps,
- Video card failure.
#6 A: Foreboding silence
Oh you don't hear a beep. I'm so sorry, nothings more irritating in programming than no error message. Lets check your bases.
Check the speaker
First are you sure your computer can make sound? If at all possible try checking your speaker on another computer. If you're using external speakers be sure that the audio cable is hooked from your motherboard too your tower.
Check the power connections
Double check that the power supply is connected to the motherboard, its plugged into the wall, the On/Off switch is turned to on.
Its your motherboard or your processor
If your computer worked yesterday then it's probably not the processor. Test whatever you can before you move your processor. This is the last act of desperation. Start by carefully removing the heat sink. Clean off any thermal paste using a cotton cotton ball and very pure (99%) alcohol.
Here's a video on handling thermal paste on your processor and heat sink.
Check the CPU socket and bottom for any bent pins or corruption. Do not, for any reason, touch the bottom pins or the pins that it connects to on the mother board.
If everything looks normal then you have to either put the processor in another motherboard that you know works. Or put another CPU that you know works in this motherboard. Only by confirming them with known working parts can you be sure what works before you purchase replacements.
#6 B. You hear a beep, try adding RAM
Once you hear a POST beep try adding back one stick of RAM. Be sure its in the primary RAM slot, there usually labeled right on the mother board.
If you get the same beep you know the RAM is good; power down and add another RAM stick and repeat until all RAM is in.
If you hear long beeps or one continuous beep then the RAM is bad and you may have found your problem.
#7. Your RAM is happy, now try your graphic card
Next try your graphics card. Listen for the beep. One beep means your system is normal.
One long beep followed by two short beeps is the signal for a dead graphics card and you've found your issue.
#8. If all beeps point to yes then
At this point you should have your processor in your mother board, your RAM and video card installed. If you still have a beep then you have your computer basically built. All that's left is the had drive and whatever optical (DVD/Blue ray) drives you want; go ahead and hook them up.
If after you you connect your drives the beep stops then I would fist double check that my power supply is enough to run everything.
#9. Don't forget your fans
If everything runs plug in your fans. Generally if a fan is broken it just doesn't spin so its not likely that their the problem. If the computer doesn't start then again I would check that the power supply is enough because that's about the only reason a fan could stop your start up.
If you do need to find the offending fan just add them one at a time and find the offender by process of elimination.
I hope this list helped, I know what its like to push the button and have no response. Just remember what its like to see the warm glow of the fans after you've debugged the problem.