Troubleshooting - Why Won’t My Computer Boot to Windows

If your computer isn’t loading your operating system and you’re stuck at the BIOS screen, you’ve come to the right place. 1 2 3

It can be frustrating when a PC doesn’t boot properly. Whether you’re putting a build together or your system suddenly stopped working, knowing where to start fixing a computer can be difficult. This difficulty is compounded if you can’t access your operating system.

In this guide, we’ll be covering steps to take if your computer is turning on and your display is working, but it’s not allowing you access to your operating system (OS) and is stuck on the BIOS screen. There are many potential causes for this problem, so we’ll be walking through some of the more common issues to try and get your system back up and running.

Note that if your computer isn’t turning on at all — meaning nothing happens when you hit your power button, or when you do, it turns on for a second and then turns off again — we’ve addressed that set of problems here.

If you're able to access the OS, but are still having problems, you’ll want to do some software troubleshooting. There are plenty of resources out there that can be used to address OS-related problems.

BIOS (Basic Input/Output System), is software stored on your motherboard that allows it to interact with the system hardware and control basic functions like boot priority. Newer motherboards use UEFI instead of BIOS. UEFI is an improved version of the software designed to be more user-friendly and ensure compatibility with newer hardware.

Think of it as a simple operating system for your motherboard that tells the computer how to start. The BIOS is what you see before your operating system loads, and usually consists of a text menu or a simple interface that allows you to control the basics of your hardware. This includes modifying startup instructions and troubleshooting.

BIOS can vary between motherboards, so there aren’t universal instructions for operation. Though the interfaces vary by manufacturer, they function similarly. For questions regarding your specific BIOS, check your motherboard’s documentation.

Depending on the specifics of your situation, it might make sense to jump to a specific section of this article. If you’ve plugged in a new USB peripheral such as a keyboard, mouse, or headset, continue reading. If you’ve recently added a new storage device, start with the “Updating Your BIOS” section. If your computer has never successfully booted, the “BIOS Error Messages” section might be the best place to start.

Eliminating External Factors

Before changing any settings, try to unplug all attached peripherals from your computer. This includes everything other than the power cable, the display cable attached to your monitor, and a keyboard to navigate menus. Attached peripherals like external hard drives or even USB-powered mice can potentially cause issues with power, driver conflicts, or issues with boot order, and can keep a system from booting to the OS.

If your system successfully boots to your OS without any devices plugged in, attach each one individually, and restart until you find the peripheral causing the problem.

BIOS Error Messages

Once you’ve eliminated external peripherals as a culprit, it’s time to check the BIOS for error messages.

Often, if the BIOS detects a hardware issue, it will tell you before you even have access to the BIOS menu. The error message will vary depending on the BIOS you’re using and the problem at hand, but here are a few examples for reference:

  • CPU fan not detected - Fan or cooler issue.
  • BOOT Device Error - There is an issue with one of your storage drives.

If you do encounter an error, and it’s not immediately apparent what the issue is related to, look up the specifics in your motherboard documentation or online. This can be an important step in identifying where the problem lies and taking the next steps toward correcting it.

If you’re still having trouble getting into your OS after exploring and addressing any error messages, it might be time to reset your BIOS to its default state.

Restoring the Defaults

A word of warning: BIOS controls the fundamental operation of your system, so be cautious when making changes.

1. If not already there, access your BIOS Menu. This process will vary depending on the manufacturer, but it usually involves pressing a key immediately after turning on your system — often the F2 or DEL key. Most systems will tell you the proper key onscreen immediately after booting. Tap this key repeatedly as soon as you turn on the system, and you should find yourself at the BIOS menu.

2. Reset to default settings. You’ll want to look up how exactly to do this based on the manufacturer of your motherboard, but this option is often located in the “Save and Exit” section of the menu. This will reset your BIOS settings to defaults, which may help to alleviate issues caused by altering the configuration. Save and restart to apply the changes.

Updating Your BIOS

This might not be as relevant if you are using a pre-built machine, or if your computer was working and then began malfunctioning, but if you are building a new PC, and especially if you are using an older motherboard, updating BIOS can be useful when troubleshooting boot issues.

Again, the process will vary slightly depending on the manufacturer, so it’s worth looking up the specifics. Your motherboard manufacturer likely has the proper procedure documented in your motherboard manual or online. Many manufactures have differing processes, and some high-end motherboards even have self-update features.

Updating the firmware can solve problems caused by pairing newer hardware, such as storage drives with higher capacities, with older motherboards.

Storage

The OS is installed on a storage drive, so the failure to load that OS can be indicative of a problem with the drive. There are a few ways to diagnose storage issues. We’re going to start with the boot order.

The boot order, or boot priority, is the order in which your PC scans available storage options and decides which ones to prioritize. If the OS drive isn’t the highest in the boot order, this could explain why it isn’t properly loading. Adjusting these settings allows you to boot from a disc or external storage, which can be useful for something like the BIOS update mentioned above. This can also cause problems if the boot priority is incorrect, or if your system is not detecting the primary storage device.

1. Remove external storage. To determine your boot order, restart your system, unplug any external storage or flash drives, and enter the BIOS by pressing the appropriate key during the startup process.

2. Navigate to the Boot section of the BIOS. The name might be slightly different, but you’re looking for the section dedicated to storage, likely called the Boot Priority or Boot Order menu.

3. Determining the proper Boot Drive. The primary drive should be the one with your OS installed. If you don’t know which drive to boot from, you may need to look at the drive itself, as the capacity and brand is often evident on the label, and this information is often referenced within the BIOS as well. If you aren’t sure which of your drives has the OS, disable all but one drive in the BIOS, and see if the system boots. If it doesn’t, continue the process of elimination until you’ve found the correct drive. You can then go back into BIOS and re-enable the other storage drives. Just be sure the drive with your OS is at the top of the priority list.

4. Save changes. Once you have properly prioritized the boot order, save changes and exit.

If BIOS is not detecting your drive at all, meaning the disk with the operating system is not appearing in the boot order menu, you could be looking at an issue with the drive itself or how it is configured.

If you’re using PCIe based storage, such as an NVMe SSD, that could also cause issues if your setup is not properly configured. PCIe is the serial interconnect that allows the chipset and CPU to connect and communicate with hardware installed into your motherboard. There are a limited amount of PCIe “lanes” (the channels that send and receive data) that need to be properly distributed among the hardware that use them, including your GPU, expansion cards, and some storage solutions.

If improperly allocated, this can result in decreased performance or compatibility issues. This is more of a consideration when initially building a computer that has never successfully booted, or when adding new hardware to an older system, as it’s unlikely lane allocation would change without installing or removing hardware.

Also, consider whether or not your motherboard supports the proper boot mode for your SSD. If you’re using an NVMe M.2 storage drive or add-in card, for example, your motherboard/BIOS might not have the capability to boot from the newer format. It might require updating your BIOS to enable a newer UEFI with NVMe boot support, or switching over to a UEFI boot mode in order to use the new drive. Most modern motherboards with M.2 slots will not have this issue, but if you’re working with legacy hardware, it’s worth exploring these options in the Boot section of your BIOS, or updating to the newest version of the motherboard’s software.

Consult your motherboard documentation to learn exactly how your motherboard handles PCIe allocation and whether or not it has UEFI compatibility. Refer to this guide for more information on booting from NVMe-based SSDs.

More About PCIe*, UEFI, and Storage

If you’re using PCIe based storage, such as an NVMe SSD, that could also cause issues if your setup is not properly configured. PCIe is the serial interconnect that allows the chipset and CPU to connect and communicate with hardware installed into your motherboard. There are a limited amount of PCIe “lanes” (the channels that send and receive data) that need to be properly distributed among the hardware that use them, including your GPU, expansion cards, and some storage solutions.

If improperly allocated, this can result in decreased performance or compatibility issues. This is more of a consideration when initially building a computer that has never successfully booted, or when adding new hardware to an older system, as it’s unlikely lane allocation would change without installing or removing hardware.

Also consider whether or not your motherboard supports the proper boot mode for your SSD. If you’re using an NVMe M.2 storage drive on add-in card, for example, your motherboard/BIOS might not have the capability to boot from the newer format. It might require updating your BIOS to enable a newer UEFI with NVMe boot support, or switching over to a UEFI boot mode in order to use the new drive. Most modern motherboards with M.2 slots will not have this issue, but if you’re working with legacy hardware, it’s worth exploring these options in the Boot section of your BIOS, and / or updating to the newest version of the motherboard’s software.

Consult your motherboard documentation to learn exactly how your motherboard handles PCIe allocation and whether or not it has UEFI compatibility.

Hardware Issues

If your system has successfully booted in the past, but the BIOS no longer detects the storage drive, you could be looking at an issue with the drive itself.

If this is the case, it’s time to troubleshoot the hardware, which will involve opening your system.

Before doing so, be sure to unplug your power cable, ensure you know the safest way to open your case, and keep in mind if working on a pre-built system that you could be potentially violating your warranty. Check with the manufacturer of your system if that’s a concern.

Once your system is open, check that the cables attached to your storage drive are properly connected and aren’t loose. If you’re using an M.2 drive, check that it is properly seated in the correct slot on your motherboard.

If everything looks fine, it might be time to remove your storage and test it with another system that you know works. If you can install the drive into another functional system for testing purposes, that would be ideal. If not, there are USB adapters that will allow you to plug the drive into the USB port of another system to check to see if the drive is detected. This will allow you to see if another OS is able to detect the drive, and run diagnostic checks using tools like Windows Disk Utility or the Intel® Solid State Drive Toolbox to determine the status of the drive.

If the storage device still isn’t detected, even on a different system, this could mean the drive has failed. If the drive is no longer operating, it’s probably time to start looking for a replacement.

CMOS

Though it’s not a common occurrence, occasionally CMOS battery issues can prevent your system from properly starting.

The CMOS (complementary metal–oxide–semiconductor) battery on your motherboard is a battery-powered chip that stores essential system information like basic hardware settings and the date. The failure of the CMOS is often indicated by a constantly resetting clock, or a BIOS error message involving the CMOS. The lifespan of these batteries is usually around a decade under typical usage conditions, but this can vary. If you’re using an older or used motherboard, double checking that the battery is operating properly is worth trying. They are relatively affordable, and the replacement process is usually straightforward.

1. Find the battery. Locate the CMOS on your motherboard (it’s a silver, flat, coin-shaped battery.) If you have trouble finding it, consult your motherboard documentation.

2. Reseat the battery. Before attempting a replacement, pull the battery out, and reseat it. Removing the battery should be fairly straightforward. There may be a latch or clip holding it in place, but usually they can simply be removed by hand or gently with a screwdriver, and replaced in the same way.

3. Remove and replace the CMOS battery. If reseating doesn’t fix the issue, try a replacement. The most common CMOS battery is a CR2032, but when you remove the battery, be sure you take note of its features in order to find an identical replacement.

4. Restart your system. After you've successfully reseated or replaced the battery, restart your system, and enter the BIOS. You’ll then want to reset your date and time settings, save, and exit.

Other Hardware

Beyond storage, it’s possible that other hardware is causing a failure to boot, especially if indicated by an error message. It’s worth checking all of your cabling, and ensuring all of your other hardware is properly seated if nothing else is working. You can follow this guide for a step-by-step breakdown of how to test your hardware piece-by-piece, and see if this solves the issue.

Further Testing

If you’ve tried all of the above recommendations and are still stuck on the BIOS screen, testing your current hardware configuration with a new motherboard might be a useful next step. This requires reinstalling your CPU, cooler, and reattaching all necessary components, but will help to eliminate the motherboard as the issue.

Testing with replacement hardware is always ideal if you have that option, and can be particularly useful if your BIOS pointed you in the direction of a particular component.

Most PC issues can be fixed, but If you’re working with an older system, it might simply be time for an upgrade. Computer hardware can last for a long time when properly maintained, but as PC technology continues to advance, even the most reliable components need to eventually be updated for the ideal user experience.

Product and Performance Information

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