What the BIOS Actually Does
The BIOS is a small piece of firmware built into your motherboard. It's the first thing that runs when you press the power button, before Windows or any other operating system loads. Its job is to check that your components are present and working, initialize them, and hand control over to the operating system so it can boot.
It also stores your low level hardware settings: which drive boots first, whether your RAM runs at its rated speed, fan curves, and various compatibility settings for the CPU and other parts. Because it sits below the operating system, a BIOS problem can cause issues that look like hardware failure even when every part is fine.
What a BIOS Update Actually Changes
A BIOS update replaces this firmware with a newer version released by the motherboard manufacturer. These updates usually include a handful of specific changes: support for newer CPUs that didn't exist when the board first launched, fixes for memory compatibility issues, security patches, and general stability improvements for specific hardware combinations.
Manufacturers list what each update changes in a changelog on their support page. It's worth actually reading this before you update, because most updates fix something specific rather than being a general improvement. If the fix doesn't apply to your situation, there's less urgency to install it immediately.
When You Genuinely Need One
The clearest case is a new CPU that isn't recognized by an older board. Motherboards ship with whatever BIOS version existed at the time of manufacture, and if you buy a board that's been sitting in a warehouse for a while, it may not support a CPU that launched more recently. In this situation, the system won't boot at all until the BIOS is updated, which creates an awkward chicken and egg problem since you often need a different, older, compatible CPU to boot the board in order to run the update in the first place. Many manufacturers solve this with a BIOS flashback feature that lets you update using only the motherboard and a USB drive, without needing a CPU installed at all. Check if your board has this feature before you buy parts.
Other solid reasons to update include a changelog that specifically mentions a stability issue you're experiencing, a memory compatibility fix for the exact RAM kit you own, or a security patch for a vulnerability that's been publicly disclosed. If none of these apply and your system is running fine, there's no strong reason to update just because a newer version exists.
When You Should Leave It Alone
If your PC boots reliably, runs stable, and does everything you need it to do, updating the BIOS purely because a new version is available isn't worth the risk. This is one of the few areas of PC building where "if it isn't broken, don't fix it" genuinely applies.
This is especially true right after finishing a build. Get everything stable first, run it for a while, and confirm there isn't an existing problem you're solving before introducing a firmware change on top of a system you haven't fully tested yet. Updating BIOS and troubleshooting a new build's stability issues at the same time makes it much harder to tell which change fixed or caused what.
The Real Risk: A Failed Update
The reason people are cautious about BIOS updates isn't that the new firmware itself is dangerous. It's that the update process can fail partway through, and if it does, the motherboard can be left in a state where it won't boot at all, sometimes called being "bricked." This usually happens from a power interruption during the flash, using the wrong firmware file for your exact board model, or pulling a USB drive at the wrong moment.
This is a real risk but a manageable one. It's not a coin flip, it's an outcome that almost always traces back to one of a few avoidable mistakes, which is exactly why the next steps matter more than anything said so far.
How to Update Safely
Start by downloading the BIOS file only from your motherboard manufacturer's official support page, searching by your exact model number. Boards often come in slightly different revisions, and installing firmware meant for the wrong revision is one of the most common causes of a failed update.
Use a USB drive formatted to FAT32, with only the BIOS file on it, ideally extracted from any zip folder it came in since some boards want the raw file rather than a compressed archive. Plug your PC into a wall outlet rather than relying on battery backup or an unreliable power strip, and if you have a laptop, make sure it's fully charged and plugged in as an extra safeguard. A power cut mid flash is the single most common way an update goes wrong, and it's the easiest one to prevent entirely.
Most current motherboards have a built in BIOS flashing utility accessible from within the BIOS menu itself, which is generally safer and simpler than flashing from within Windows. Follow the on screen instructions exactly, and once it starts, don't touch anything, don't turn off the power, and don't remove the USB drive until it explicitly tells you it's finished and has restarted on its own.
After the Update
Once the update completes and your system boots back into the BIOS menu, check your settings. A BIOS update sometimes resets custom settings back to default, including RAM speed profiles and fan curves you had configured before. Re-enable anything you had set previously, save the settings, and then boot into your operating system to confirm everything is running normally.
It's worth doing one more stability check after any BIOS update, particularly if the update touched memory compatibility or CPU support. Run your system under normal use for a day or two before assuming everything is fine, since some issues only show up under sustained load rather than immediately after restart.
A BIOS update isn't something to fear, but it also isn't something to do casually just because a notification popped up. Check whether the update actually fixes something you're dealing with, follow the process carefully, and you'll get through it without any drama.