Quick Guide to Fixing Computer Hardware

by Howard Fosdick                                                                 Updated: December 2020
                                                                                                   Originally published in OSNews in 2012

Even those with no training -- like me -- can identify and fix the most common computer hardware problems. This is your quick guide to doing exactly that.

Here's the outline --

Step 0: Identify the Problem
Laptop Unexpectedly Shuts Down
Computer Turns On But Won't Boot
Computer Won't Turn On
Computer Boots into Windows But Fails Somewhere Along the Way
Computer Loses Date and Time
Mouse Problems
Keyboard and Display Problems
Optical Disc Problems
Memory Errors
Disk Problems
Hard Disk Problems
Port Problems


  1. Before you open up your computer, remember to unplug it. Unplug everything.
  2. Ground yourself! A small shock you won't even notice can kill circuitry. Buy a $5 USD anti-static wrist strap.
  3. Enter error messages to Google to see how others fixed your problem. Why reinvent the wheel?
  4. Download your computer's User Guide and Field Service Manual if you don't have them. Most companies offer free downloads.
  5. A 2" long Swiss Army Knife includes a tapered screwdriver that fits nearly all PC screws for about $15 USD.

Step 0: Identify the Problem

The first step in fixing any problem is to identify it. Don't jump to conclusions. Run free diagnostic software for problem identification:
Don't know if your problem is hardware or software? Run a different operating system. If the problem disappears, it's software. If you're using Windows, boot a live Linux from USB or DVD to determine whether your problem is Windows or a hardware issue.

Here are the most common hardware problems and their solutions:

Laptop Unexpectedly Shuts Down

There could be many causes for this one -- a short circuit, damaged electronics, and more. Most random shutdowns are caused by overheating. Laptops are prone to this because they cram so much circuitry into too small a package for easy cooling. But it can happen to desktops, too.

Every computer has internal sensors that immediately shut down the system to prevent electronics damage if the temperature gets too high. Since you can not relate the timing of the shutdowns to your actions, they appear random.

View your laptop's internal temperatures by running a free monitoring app. Download SpeedFan or other free monitors for Windows or use lm-sensors for Linux.

To fix overheating, ensure all fan(s) are spinning when they should. Unclog the air vents. Make sure you aren't blocking the vents by placing the laptop on your lap or pushing your desktop up against a flush surface. Don't pre-heat a laptop by leaving it in the direct sunlight or in a car window. Use the computer in an air-conditioned room.

Open the computer and remove dust, especially that coating circuitry. Since static electricity kills electronics, don't rub circuitry with a dust rag. Blow out dust with an inexpensive canister of compressed air.

If this doesn't fix your problem, you may need to replace the fan(s). Fans burn out as their ball bearings fail. Here's how to replace a case fan. If the computer has a CPU heat sink (a metal flange that draws heat away from the CPU), you may need to re-seat it. Here's how to re-seat a CPU heat sink and the CPU.

Anyone who's downloaded their computer's service manual can perform these procedures so long as they exercise care. 

Computer Turns On But Won't Boot

You flip the power switch on and your computer appears to start up. The power light goes on, the fans spin, maybe the disks kick -- but nothing further happens. You can't get into the computer's configuration (UEFI/BIOS) panels to perform problem determination. That means you have a hardware problem.

Some computers will give you "beep codes" or flash panel lights to tell you what's wrong. Look in your machine's doc to decode them. Or visit this webpage.

Without beep codes or other indicators, this one's tough to diagnose. You need a methodology to identify the problem. Here is one that is time-consuming but effective in isolating a defective component. It identifies these problems:
To start, turn off and disconnect the computer from power, open it up, and write down where every wire, insertable adapter card, and connector attaches to the motherboard and the devices. Record this so you can reattach everything later. Then disconnect every wire or plug from the motherboard, except for the power connectors from the power supply. Detach all devices. Remove all adapter cards and all memory.

Now you're down to a naked motherboard with its CPU, attached to the power supply. Insert one good memory stick into the first slot nearest the CPU, attach a working display (with a video card you know works, if necessary), and turn on the computer. If you can't access the configuration or UEFI/BIOS panels now, the motherboard or CPU circuitry may be bad. Visually inspect the motherboard for leakage, especially near the capacitors and battery. You might succeed in cleaning up leakage, but most of these boards are goners.

If the system does display the UEFI/BIOS panels, the motherboard and its embedded circuitry is good. One at a time, reattach each connector or cable or insertable adapter card. After reconnecting an item, turn on the computer. If you can still get into the UEFI/BIOS panels, you know that whatever you just attached is not causing the freeze-up or failure. As soon as you attach an item and the computer dies, you know that that component was the problem.

Here's an example. My friend's year-old computer completely baffled him. It would start up, display the "HP Welcome" panel, and freeze. He couldn't get into the configuration panels. I stripped the system down to the Motherboard+CPU+OneMemoryStick+Display+PowerSupply. Then I powered on and got into the UEFI/BIOS panels, so I knew the motherboard and CPU were good. Then I attached each item, one at a time, and booted after each, and got into the UEFI/BIOS panels. Until I attached the SATA disk drive! Then the symptom re-appeared. We replaced the defective disk and the system has worked fine since.

Computer Won't Turn On

What if your computer won't turn on at all? Check the power supply and ensure it's getting electricity. Was it plugged into a live wall socket with a good power cord? Test the socket with a lamp. Don't assume that one socket in a power strip is working just because the other sockets in the strip work. If you just upgraded memory verify the secure seating of the ram sticks.

Check the wire that goes from the Power On button to the motherboard. If this doesn't connect you're not turning on the computer at all. Is the power supply (PS) working? Did its fan spin when powered on? Is the PS properly connected to the motherboard?  If you have a spare try the motherboard with another power supply to see if a burnt out PS is the problem. Find how to diagnose PS problems here. If you have a volt-ohm meter (VOM) verify the current.

If these procedures don't work, try the disassembly/reassembly procedure above. Sometimes you'll find a short caused by improper connection this way.

Computer Boots into Windows But Fails Somewhere Along the Way

If the computer boots and gets into the Windows start-up process, then freezes or fails, nearly always you have a Windows software issue rather than a hardware problem. To find out for sure, boot a live Linux from USB or DVD.  If everything works you have a Windows problem. This is a hardware article so I won't address how to fix Windows.

Computer Loses the Date or Time

If your computer loses the date or time across sessions, you probably have a dead battery. This is the little round watch-type battery that keeps configuration information across sessions, the CMOS battery.

Before you replace the battery, write it down any unique configuration information you've entered into your UEFI/BIOS panels. Because this procedure will erase it.

Now, pry out the battery and replace it. They cost only a few bucks. After you install the new battery, update the date and time and re-enter any unique configuration info into the UEFI/BIOS. Here's how the battery might look on a desktop's motherboard:

 CMOS Battery
Courtesy: www.PCTechNotes.com and www.TechNibble.com

Mouse Problems

With optical mice, the only cleaning you need to do is to ensure that no lint is clogging the optical opening beneath the mouse. Sometimes optical mice don't track well on glossy or transparent surfaces, including some mouse pads.

If your plug-in mouse doesn't work at all, ensure the connection is secure. Verify the operating system is using a valid mouse driver. Test your questionable mouse on another computer or plug in a different mouse to your computer. Reboot and test. This shows whether you have a dead mouse rather than a software issue.

If your mouse is wireless, the most common problems are: (1) a dead battery (2) a wireless connection problem (3) device drivers that are not correctly installed, or (4) a dead mouse. Check the batteries first. Ensure the wireless adapter or USB linking device is securely plugged in. Verify the drivers. Use the wireless control program to diagnose and resync the mouse. Try resyncing the mouse by powering everything down, then rebooting.

Keyboard and Display Problems

If you prevent food, hair and other debris from falling inside your keyboard, you've avoided 90% of all problems. To clean a keyboard, detach it, turn it upside down and vigorously shake it. If this doesn't work, carefully pry off sticky keys and eliminate the gunk underneath.

Desktop keyboards are so cheap you might as well buy a new one for all but the simplest repairs. Laptops are another matter, with their embedded keyboards. Here's a good article on repairing laptop keyboards. And here are several instructional Youtube videos. Hiren's Boot CD includes keyboard testing programs.

What if you spill water or a drink onto your keyboard? Turn everything off immediately. Pull the power cord or push the Off button. Do not take the time to perform a graceful shutdown! The longer electricity goes through the electronics the greater the chance for permanent damage.

Do not touch or move the keyboard. Wait a full day to ensure everything has dried out. Then, turn on the system. If you're lucky it will work.

Cleaning the keyboard with rubbing alcohol or electronics cleaner may be in order if you spilled a drink that will become sticky after it dries. If you spilled water, don't bother. Just let it all evaporate.

The principle about wet keyboards applies generally to computer electronics. I've picked up computers left out in the rain or snow, let them dry out, and used them without any ill effects. Just dry them out completely before powering on!

Desktop displays are black boxes. The usual remedy is replacement. But verify you don't have a device driver or software issue before junking your display. With laptops you have to buy a replacement screen for your specific laptop model and install it. Here are some Youtube videos showing how to replace laptop screens. Anyone can successfully replace laptop screens and keyboards -- if they download model-specific documentation and follow it carefully.

Sometimes you'll get a stuck pixel on a LCD screen, a pixel that inaccurately remains an out-of-place color like green or red. Use a felt cloth to gently rub around the bad pixel in a circular motion. If you can get the pixel to light properly, hold the pressure there for a minute or two, and this often fixes it.

Optical Disc Problems

If your optical drive doesn't work, new ones are cheap. But first check all connectors, ensure the OS recognizes the device, and that you have a working driver installed.

What if the problem is sporadic? Try cleaning the drive with these simple cleaning techniques.

Another possible cause is differing calibration between drives. It's possible to write a disc on one system and find another unable to read it. Determine if you have a calibration difference by testing multiple discs on several different drives.

You might find that your drive works well with certain brands of disc media but not with others. Media differences can cause sporadic problems even with healthy optical drives. Remember that there are many optical media standards and that you have to match them properly to the drives that use them. While current drives support multiple media standards, you can't always mix all media in all drives (DVD+R, DVD-R, DVD+-R, DVD-RAM, Blu-ray, CD-RW, CD-ROM, etc).

What if your problem is a particular disc? Clean the disc by gently rubbing it from the inside towards the outer edge. Remove any fingerprints. Sometimes wiping with a dab of distilled water will work. Other times, more aggressive techniques are necessary. This article has a progressive list of steps you can work through to restore a disc to a readable state. It includes my favorite -- cleaning the disc with toothpaste. It often works! But read the entire article before you try it.

What if a DVD gets stuck in the drive? Look closely at the drive face and you'll see tiny hole. Stick a straight pin in there and push a lever that will mechanically push out the tray. Do this with the computer powered off since it is solely a mechanical procedure.

Memory Errors

Memory errors are easy to fix. Simply remove and replace the bad memory stick. The problem is identifying that you have a memory error, since many are transient (they occur sporadically). If you suspect a memory problem, run an intensive memory checker utility like Linux's Memtest86 or Hiren's Boot CD. Take the time to run the long or extended test (not the short or quick test). Run it overnight if necessary.

You can also set the UEFI/BIOS configuration to test the memory upon startup at the expense of a longer boot. This test will not be as thorough as Memtest86 or Hiren's.

When you add memory into your computer, ensure it's seated correctly before booting. If the memory is not inserted properly most computers will beep and refuse to boot, telling you to re-seat. Hopefully no damage resulted. After adding memory, enter your UEFI/BIOS configuration panels to ensure it's properly recognized before booting all the way into your operating system.

Disk Problems

A million things can go wrong with disks. If it's a software problem, you can fix it. If it's a hardware problem, buy a new disk. Messing with faulty disk hardware is not worth your time -- with two exceptions:
  1. You need data only available from that disk (you don't have a data good backup)
  2. You need to save your copy of Windows and the installed applications (you don't have a backup of Windows and the apps, and have no way to recreate them)

The best insurance against disk failure -- by far -- is good backups!

To test if your disk is working, most computers' configuration panels (the UEFI/BIOS startup panels) have drive diagnostic and test procedures. You can also download the disk drive manufacturer's free drive-specific diagnostic program, which is often more effective than the computer's own tests.
Here are common disk symptoms and how to fix their underlying problems:

"Operating System Not Found" Error

When booting your computer, you might get an error message like one of these:
These are all software errors. Your computer is telling you that the boot record and/or partitioning data stored on the disk are either missing or corrupted. You can often fix this issue using tools like free TestDisk utility. Here and here are tutorials for Windows users.

OS Detects the Drive But You Can't Access Your Data

Sometimes Windows knows a drive is present but won't let you use it. Or it tells you the drive needs to be formatted. Or maybe it just shows a blank drive that doesn't contain any data. Or it won't show you the drive properties or let you format it. Usually this means a software problem: filesystem corruption.

You can fix a filesystem to recover all or nearly all of your data.  Here is a quick list of fix/recovery tools (with more here):  

Filesystem: Free Repair Tools:

FAT32, VFAT TestDisk, Disk DiggerPCInspector File Recovery, Linux dosfsck utility
NTFS Lots of free and shareware tools here, Ubuntu's tools, DTIDATA's toolTestDisk
ext2, ext3, ext4
Use built-in Linux utilities like fsck, e2fsck, ddrescue, etc., TestDiskDiskInternals

It's possible to have a hardware problem that shows the same symptoms. Dirty contacts between drive and cable are one possible cause. Just clean the contacts with a Q-tip, toothbrush, or pencil eraser. Many use isopropyl alcohol (90% grade or better) with their cleaning tool. Just use don't drip the alcohol anywhere and make sure you leave no Q-tip fibers or eraser crumbs behind!

Drive is Not Detected At All

Make sure that drives have fully connected power and data cables. You could get a variety of errors from this but "drive not detected" is common. Check the data cable connection to the motherboard as well as the side that connects to the back of the drive.

Hard Disk Problems

If you're still using old hard disks (HDDs), they have their own set of issues. They have mechanical features that newer solid state disks (SSDs) lack, such as spinning platters and movable read arms.

Rules of thumb for fixing hard drives:

Hard Drive Makes Clicking Noises

This is the so-called Click Of Death. Drives make clicking noises when they have to move the disk arm multiple times to retrieve data. The drive is not functioning properly and this is its error correction procedure. Your drive may fail very soon! Copy any data you need off there immediately. You may have limited time so copy files in priority order.

If you can not get in to copy data off by normal means, here is a procedure that extracts data from even the most recalcitrant drives. It's more detailed than I can describe here but the key steps are:
  1. Hook up a second target drive to the controller (or you can use a USB thumb drive as the target)
  2. Use the ddrescue command to copy the raw drive image from the failing drive (instructions here)
  3. Make the target partition active so you can access your recovered data
ddrescue tries every trick in the book to read the data off the target drive, bit-by-bit, regardless of what filesystems or partitions the drive contains. It will even try to read the data backwards. It's very effective. But it might take many hours or even days to get your data back. Like all the software in this article it is free.

Drive is Not Detected At All

First, always make sure that the cabling connecting the drive to the motherboard is fully seated at both ends. This is the most common problem.

Another possible cause of "drive not detected" problems is a failed logic card on the drive. This is the circuit board attached to the underside of the drive. The board circuitry may fail over time due to the heat coming off the drive and the temperature differential from the powered-off state.

Take off the drive's circuit board and replace it with another. You can buy one on the web or take one from another drive. The key to success is that the logic board must be for the exact same drive. If not, it will not work. Obviously, you'll only go to this trouble if you really need the data on the drive and have no backup!

Hard Drive is Not Spinning

If the drive is not spinning, most people assume it is dead. Usually, but not always. I've read about supposed home remedies like freezing or hitting the drive. But if you really must retrieve your data from that drive, don't mess with it! Instead, pay a professional data recovery service, like Data Savers or Ontrack. They often succeed because they ignore the drive hardware and instead directly analyze its storage media.

Port Problems

Your computer has many different kinds of "ports" (or plug receptables). These include ports for USB devices, SD and similar memory cards, monitors, sound and speakers, microphones, and so on. From the hardware perspective, the most common problem is dust getting into ports that aren't frequently used. Make sure your computer is turned Off, then clean the port by a Q-tip or toothbrush, if necessary enhanced with a small drop of isopropyl alcohol (90% grade or better). Check inside the computer to ensure that no connecting wires from these ports have become disconnected. Lastly, verify that your operating system detects the port and has installed a suitable driver for it (if needed).


There's much more to fixing computer hardware than any one article can cover. Yet this quick overview solves perhaps 90% of all hardware problems. Yes, you can fix it!

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Howard Fosdick is an independent consultant who supports databases and operating systems. He fixes old computers for fun and charity. Read more how-to's and tutorials here.


FixingMyComputer.com Basic but comprehensive
GeekyProjects.com Good tips
Computer Repair with Diagnostics Flowcharts,
The Laptop Repair Workbook
Includes flowcharts for diagnostic repair
Yahoo Answers Post and review questions

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