Common New Computer Problems and How to Solve Them
Just built a computer and running into issues? Is your previously-working computer now not booting up? Read on.
1. Power but no video
I just put together my new computer. I go to power it on and all the fans go, I hear the hard drives spinning up, I can open the CD drive, but I don't see anything on the screen!
An unfairly large number of things can cause a computer to not boot up properly. This includes, but is not limited to:
Bad motherboard
Electrical short caused by the motherboard not being raised high enough off the case. Double-check to make sure your spacers are installed on the case underneath the motherboard.
Bad processor
Bad RAM
Improperly seated RAM, or RAM in a bad configuration (Check your motherboard manual for which slots your RAM should go in)
Bad video card
Improperly seated video card - make sure you have it pushed in all the way
Bad power supply
No external power connected to video card (Only some video cards require this)
Inadequate power supply
Improperly connected power supply (Many newer motherboards require that extra square 4-pin molex connector from your power supply to be connected to the motherboard somewhere)
Any number of bad PCI devices (IDE/SATA controller card, LAN card, sound card, etc)
Improperly wired case front panel connectors - USB connector, power or reset switch, etc
Mouse or keyboard hooked into the wrong PS2 port (Thanks j4cbo)
Basic Troubleshooting
To begin, start with the first steps in basic troubleshooting:
Remove the motherboard from the case
Set it on a piece of cardboard - like on top of the motherboard box
Remove everything connected to it
ONLY leave in the video card, one stick of RAM, and the processor and heatsink
Connect the power supply to the motherboard and your monitor to the back of the video card, and try to connect the power switch connector from the front of your case to the motherboard. If it won't reach, you can use a small flathead screwdriver to touch the two power connector pins together to turn the machine on.
Does it boot up now?
You know at least your most essential pieces are working properly. Try putting it back together piece by piece, turning it on every time you connect something until you isolate which part is causing the problem. If it stops working when you put it back in the case, you probably have a short on the bottom of your motherboard. There should be little spacers that hold the motherboard about a centimeter off of the case. Some cases will have these already installed, but other cases will require you to install those spacers yourself. If there's not enough clearance on the bottom of your motherboard, metal will touch metal in places where it shouldn't, and a "short" occurs, which can cause bad things. On the flip side, having too many spacers, especially where the case doesn't have holes for them, can also cause a short. Most ATX-sized motherboards should be fine with 6 spacers.
Still not booting up?
Make certain you have all the power connectors from your power supply hooked up. Some power supplies will have a 20-pin white molex connector that will plug in fine to a 24-pin power connector on the motherboard. If this is the case, then there should be another small square-shaped 4-pin white molex power connector that plugs into a similarly-shaped connector on your motherboard.
Access to another power supply? Give that a shot.
Have another video card you can try? Swap that in.
Any other RAM you can try? Swap that in and give it a go.
If by the off chance you have a spare processor you can try, give that a shot, too.
Try resetting the CMOS. There should be a 3-pin jumper on your motherboard, usually labelled CMOS or JBAT or something similar. There's a little plastic jumper that will sit on pins 1 and 2 - if you move it over one, so that it sits on pins 2 and 3, then remove all power connected to the motherboard and let it sit for a minute or two, this will reset your motherboard back to all its default settings.
Some motherboards will have an LED display (EPoX boards) or a USB PCI-slot plate cover that will have two USB ports as well as four diagnostic LEDs (MSI boards) that can help in troubleshooting. Assuming your motherboard isn't toast, it can tell you exactly what's causing the issue with it not booting up correctly if you refer to the error codes in the motherboard manual.
If all else fails... time to RMA. Sorry dude.
2. Beep Codes
I turn on my newly assembled computer and it starts beeping like crazy at me. What the hell is that?
Those are known as beep codes, and every BIOS has different ones. If you know what type of BIOS you have, you can check out common codes at BIOS Central to help you try and diagnose it. Most enthusiast motherboards use either AMI BIOS or AWARD BIOS. If you're getting one long steady scream from your PC speaker, see if there's a 4-pin molex connector on your video card. Some of the beefier video cards require extra power.
3. No power, no video
I assembled my computer and I try to power it on, and nothing happens at all.
Make sure that you wired the front panel connectors correctly. Follow the diagram in your motherboard to make sure you have the right wires going to the right headers. Remember, the colored wire is always the positive side, and the white or black wire is the negative. Failing that, a small flathead screwdriver can be used to touch the two pins together that control the power to turn it on that way.
Also check to make sure the power switch on the back of your motherboard is on. For the record, I is on, O is off.
Double-check that the power supply is plugged in correctly and the 20/24-pin white molex cable is snapped in tight.
This can also be caused by not having spacers installed in your case to keep the motherboard elevated off the metal of the case. If the bottom of your motherboard touches metal, a short can occur, which usually doesn't cause damage, but prevents your motherboard from powering on properly.
4. Booting up then shutting down
My computer looks like it's powering up okay, but after a few seconds, it shuts back down again without me doing anything.
This is usually caused by your processor getting super hot very fast, and shutting itself down before you can do permanent damage to the processor. Make certain that your heatsink is making good contact with your processor - it should be very tight against the processor. Also, some heatsinks will come with a piece of plastic attached to the bottom of them. Make sure you didn't leave that on. All that should be between your heat sink and your processor is a bit of thermal paste. Retail heatsinks should come with that gummy stuff already on the bottom so you shouldn't need extra.
This can also happen if the CPU fan isn't plugged in, or plugged into the wrong fan header. Some motherboards need to detect a fan being run on top of the processor, or it'll think there's nothing there, get scared, and shut down automatically. Make sure the fan on your heatsink is plugged into the CPUFAN fan header near your processor. (Thanks j4cbo)
5. Floppy drive
Everything looks like its working but the floppy drive light stays on and is making noises.
Your floppy drive ribbon cable is plugged in backwards. Flip it upside down. There should be a red strip on the ribbon cable - that end should face the power connector. (Thanks hamiltonrmcato)
6. Drives not detected
The BIOS doesn't detect any of my drives.
If you have an IDE drive, make sure your jumper settings are correct. Most hard drives will have the jumper information on the label, and in 90% of cases the jumper configuration should be on cable select. By setting them to cable select, then the "master" drive will be the hard drive on the connector at the furthest end of the ribbon cable away from the motherboard, and the "slave" drive will be the drive on the middle connector. If you have a SATA drive you don't have to worry about any of this jumper nonsense.
Make sure your data cables are plugged tightly into the hard drives, and in the case of an IDE hard drive, that there aren't any bent pins which aren't connecting properly. If you accidently bent a pin, don't panic. You can usually bend them back gently. Just don't make a habit of it or the pins will start snapping off. If you have a SATA drive, just make sure the small L-shaped connector is plugged in tight. Also make sure that the other end of the IDE cable or SATA cable is plugged into your motherboard tightly.
Also make sure you have power connected to each of your hard drives. IDE hard drives take a 4-pin white molex connector, and SATA drives take a thin black power connector.
These steps also apply if your drive that isn't showing up is a CD or DVD drive.
7. Windows not finding hard drive
The Windows installation program isn't seeing my hard drive.
First, make sure that your BIOS is seeing your hard drives. If they aren't read the above section covering this. If your BIOS sees them, then Windows should definitely see them.
The exception to this is if you have an older or off-brand motherboard and are using a SATA hard drive. Windows can usually auto-detect the SATA controller on your motherboard and know to look for a hard drive there. However, in some cases it's necessary to tell it what kind of SATA controller you have. This is done with the floppy disk that should have come with your motherboard. When you first see the blue Window, a message will flash by saying "Press F8 if you need to install any third party SCSI or RAID controllers." Hit F8, and it will prompt you for the floppy. Pop in the floppy that came with your motherboard and follow the instructions for getting it set up.
If your motherboard didn't come with a floppy for some strange reason, sometimes it'll come with a CD that will make a floppy for you that will have the SATA controller driver on it.
Also, some BIOSes, particularly on OEM computers, will have an option for you to switch your SATA controller between being ordinary SATA or forcing it to act like a generic IDE channel, so if you're still having problems getting Windows to recognize your SATA drive, see if you can make your BIOS force your SATA controller to be, well, dumber. (Thanks Lafarga)
Version History
04/11/06 - Added bits about spacers 02/02/06 - First created