Dan earned his CompTIA (CIOS) certification in 2010 and worked in the computer repair/networking industry for several years.
Computer users appreciate a bone tossed every now and then for typical computer woes—especially as it pertains to computer startup issues. Not everyone who uses computers can afford professional assistance and therefore seek practical advice from wherever it may come.
The technology is not as complicated as it seems. Whether the operating system in use is Microsoft Windows, Apple macOS, or Linux, there are common steps that can be taken to resolve a computer that will not power on or boot correctly. It should be noted, however, that while the tips listed herein are simple, they are not always feasible for people to apply themselves without assistance.
Furthermore, this is not a comprehensive list of possible problems and solutions for computer startup problems, but instead, a guide to reference for the most common issues, assuming that only one operating system is installed. Although cooling issues can be common, in order to help with brevity, they are not covered here. If the computer is shutting down at some point during startup, it's probably due to the CPU overheating—please research computer cooling issues and solutions via the internet.
The Computer Power Button
From the moment of pressing the power button on a computer, up to the point when the "desktop" is visible on the computer screen, the computer goes through a series of phases, each with distinct characteristics. Certain audio cues called "beep codes" will sound in the early stage of startup if there are major hardware problems, which helps in the troubleshooting process. Sometimes these cues are manufacturer-specific but generally, there is common ground between them all—consult the computer manufacturer documentation for the specific beep code meanings.
Computer Troubleshooting First Steps
When pressing the power button on a desktop computer, an LED light and cooling fans will turn on indicating that the computer is generally receiving power—when these cues are absent, it indicates a power problem. Proceed to rule out a faulty electrical receptacle in the wall by plugging the computer into another receptacle.
Once this is done, the next logical place to check for failure is in the computer power supply or motherboard. For checking the power supply, an inexpensive voltmeter can be used to make sure the power supply pin-voltages are where they should be (correct voltages can be referenced on the internet)—if not, then the power supply should be replaced. Another method to check the power supply is by swapping it with one that is sufficient in wattage and known to be in working order—if the computer powers on, then it can be concluded that the problem was the power supply.
At this point, when it's determined that the power supply is working but there are no signs of the computer receiving power, the motherboard is likely the culprit. Generally, relatively old motherboards are not repaired, they are replaced due to the fact that repairing them is not economic—even if the problem is found and fixed, the likelihood of it failing again is high since computer chips and parts eventually wear out.
Moving Past Computer Power Issues
When a computer is powered on, the first phase it goes through is what's called a POST, or power-on-self-test. Built-in software (on the motherboard) checks to make sure certain hardware is working and, when completed, moves on to the next phase of the boot process.
If the POST detects hardware issues it will display details on the attached monitor, or signal with beep sounds—the beeps codes indicate what is wrong—they can be referenced in the computer manufacturer documentation. If no hardware issues are detected, the computer manufacturer (logo) splash-screen will appear, implying the POST has been completed successfully and the boot process will continue.
However, sometimes POST will not complete its hardware-checking routine, rendering a dark, blank screen—if this is the case, re-seating power supply cables, peripheral devices, and RAM might resolve the issue, as sometimes connections can become loosened.
A failed POST can also be caused by failing RAM (memory) modules—removing the suspected module and rebooting the computer can reveal which module is causing the problem, however, if there is only one module installed, the only option to rule out RAM issues is by swapping that module out with a compatible one that is known to be working. Failing power supplies can also cause the POST check to not complete and checking the power supply should be done.
Continuing The Computer Boot Process
After POST has been completed, the built-in software called the BIOS passes control of the boot process to the hard drive where the operating system is installed. Depending on the partitioning scheme being used on the drive and how the boot process is configured, a couple of different things can happen. Assuming they are working, the MBR (master boot record) or GPT (GUID partition table) located in a tiny section of the hard drive will point to the partition selected to be booted, then begin loading the operating system.
If failed, some of the visual cues present will be a stalled or slowed boot process, or "stop" errors and blue screens. Possible culprits to consider are a failing/loose drive (or drive cable), failing RAM memory, a failing power supply, a corrupt file system, corrupt operating system files, too many "start-up" programs trying to load, or malicious software (viruses)—it's possible for failing RAM memory to get past the POST, so troubleshooting RAM memory further at this point might be needed.
If the computer can be booted into "safe mode" then this will rule out hardware problems. Safe mode runs a slimmed-down version of the operating system and disables third-party programs. Another benefit of booting into this mode is that you can recovery needed files if repairing the computer is not a feasible option at the time.
To boot into safe mode in Microsoft Windows, start by first shutting off the computer—then power it back on and tap the F8 key until the safe mode boot options appear. If you need an internet connection while in safe mode, select "safe mode with networking," otherwise just select "safe mode."
Computer Hard Drive Troubleshooting
To rule out a failing hard drive, it can save time by first making sure the computer's BIOS is recognizing the device. Follow the manufacturer's guide to entering the computer's CMOS setup program—once CMOS setup is on screen, in the "Main" tab there will be noted the make/model of the hard drive installed and how many bytes of data it can hold.
If the hard drive is missing in the "Main" tab, chances are the hard drive has gone bad and needs to be replaced. However, drives that are integrated into motherboards, such as eMMC drives, cannot be replaced in a practical sense—the only option, in that case, would be attempting to work around the problem by using external drive alternatives or buying a new computer—or motherboard if you're up to replacing it.
If the drive is showing in the computer's CMOS settings, using software tools downloaded from manufacturers or third parties can be installed onto a USB flash drive and configured as a boot option in the computer's CMOS settings—to be used for further troubleshooting. It should be noted, however, that if RAM memory is failing, booting from a USB flash drive might be unsuccessful—rule out faulty RAM memory and power supply issues before moving on.
Advanced Computer Troubleshooting Steps
Even though hard drives are recognized by computers as indicated in the CMOS set-up program, sometimes their individual memory locations, also called sectors and blocks, can go bad, and checking for these issues can be necessary.
However, if there are mission-critical files or data stored on the computer, consulting with a data-recovery expert should be done to determine the cost of recovery—attempting to scan hard drives can further the damage and render subsequent data recovery attempts useless.
Using a working computer, install the scanning software to a bootable USB drive and boot it, to scan the drive for faulty drive memory locations. If problems are found by the scanner, drive replacement procedures should be taken which implies an eventual reinstallation of the operating system.
Once faulty hard drive sectors are ruled out, ruling out other culprits is next—the same troubleshooting software (typically a multi-featured program) can be used to test RAM memory, check for a corrupted file system, and repair/replace corrupted operating system files.
Operating systems, however, have ways to limit what programs start when a computer is powered on—if installed software is suspected to be causing a problem, it can be disabled by following a few simple steps in order to rule it out—consult the procedure available for the operating system installed. Malicious software can be ruled out or fixed by following recommended procedures for the given symptoms and the situation in general.
Exploring Computer Help Resources
The steps outlined herein for troubleshooting startup problems are generally applicable to the three mentioned operating systems, although the procedure and features will look different onscreen depending on which is being used.
Several keywords exist herein which can be searched on the internet for more in-depth knowledge or details. The same steps can be applied to laptops, although since they are powered by batteries and chargers, troubleshooting power problems will be different. For common run-time problems with both desktop and laptop computers, see my performance boost guide.
This content reflects the personal opinions of the author. It is accurate and true to the best of the author’s knowledge and should not be substituted for impartial fact or advice in legal, political, or personal matters.
© 2021 Dan Martino