BIOS is the firmware that lives on your motherboard. It runs before your operating system, checks that the hardware is alive, and hands control over to Windows or whatever you install. On a brand new build it is also your first real test: if you can get into BIOS at all, the core parts are working.
Modern boards call it UEFI rather than BIOS, and the screens look far friendlier than the blue text menus of older machines. The job is the same though. Below is the order I set up a fresh build in, from first boot to installing Windows, along with the settings worth changing and the ones best left alone.
Getting into BIOS on first boot
Power on with your monitor plugged into the graphics card, not the motherboard, unless you are using integrated graphics. As the machine starts, tap the BIOS key repeatedly. For most boards it is Delete or F2, and the splash screen usually says which. If you miss it, let the machine boot, restart, and try again.
On a new build with no operating system installed, most boards drop you into BIOS automatically anyway. If you get a black screen instead, that is a hardware question rather than a BIOS one: check the RAM is fully seated, the graphics card is clicked in, and the monitor input is correct.
One habit that helps: have a phone or notebook ready to record what you change. BIOS settings are quick to adjust and quick to forget, and if something becomes unstable after a change, you want to know exactly what it was.
Load optimised defaults first
Before touching anything, load the board's optimised default settings and save. On a new board this is usually just tidying up whatever state the firmware shipped in, but it means every later change is one you made deliberately.
Do this first, not last. If the machine behaves oddly after your own tweaks, you can reload defaults and know the baseline works. That gives you a clean starting point for every session.
Check that everything is detected
The main BIOS screen normally lists the processor, installed memory, and connected storage. Confirm all three match what you bought. The processor model should be recognised correctly, your RAM total should match the sticks you installed, and every drive should appear in the storage list.
Missing RAM is the most common surprise at this stage. If half your memory is absent, power down and reseat the sticks in the correct slots. The board manual shows which two slots to use for a two-stick configuration, and getting that wrong can leave capacity or dual-channel performance on the table.
Also check temperatures on the hardware monitor page while you are here. At idle in BIOS, the processor should sit somewhere in the range of warm room temperature to roughly 50 degrees, depending on the cooler and the case. If it is climbing steadily while doing nothing, the cooler is not making proper contact. Sort that out before going any further, because installing an operating system on a badly mounted cooler only delays the problem.
While you are on the monitor page, glance at the voltages too. They should be close to their stated values. Wildly wrong readings usually mean a sensor quirk rather than a fault, but a quick look costs nothing.
Turn on the memory profile
This is the single most valuable BIOS change for a gaming build. Memory ships at a conservative default speed, and the faster rated speed is stored in a profile that you have to enable yourself. Depending on the platform the setting is called XMP or EXPO, and it is usually a single dropdown or toggle on the main overclocking page.
Enable it, save, and let the machine restart. Memory training on a new build can take a minute or two and the screen may go black a few times. That is normal. When it comes back, confirm the memory speed shown in BIOS matches the rated speed on the box.
If the system will not boot with the profile enabled, reload defaults, update the BIOS first (more on that below), and try again. Failing that, enable the profile and manually step the speed down one notch. Running slightly below the advertised speed is far better than leaving the memory at its slow default.
Set fan curves and cooling behaviour
Out of the box, fan behaviour is often either loud or lazy. The hardware monitor or fan control page lets you pick how fan speed responds to temperature. A sensible starting point is a gentle ramp that keeps fans slow while idle and spins them up as the processor warms under load.
If your board controls fans by CPU temperature only, remember that a graphics card dumping heat into the case can warm everything without changing the processor reading much. In that case, a slightly more aggressive curve, or a flat speed that is simply quiet enough, is the practical answer.
Pump headers matter here too. If you have an all-in-one cooler, its pump should run at full speed rather than being throttled by a fan curve. Most boards let you set a header to a pump or full-speed mode for exactly this reason.
Prepare the boot order and drive setup
With no operating system installed, the boot order is mostly a preview of what happens next. Set your Windows installation USB as the first boot device so the machine starts the installer directly. You can remove it from the list later.
Storage mode deserves a moment of thought before installing Windows. The default modern setting works for almost everyone, and changing it after the operating system is installed is a reinstall-level problem. If you are not certain what a setting does, leave it at the default and move on.
Fast boot and similar quick-start options are fine to leave enabled, though they can make entering BIOS slightly harder later. If you find yourself locked out of the settings screen, most boards offer a restart-into-BIOS option from Windows, and clearing the CMOS is the reliable fallback.
Security and firmware settings worth knowing
Two security-related settings matter for a modern Windows install: Secure Boot and the firmware TPM. Both are usually enabled by default on recent boards, but it takes ten seconds to confirm. Windows expects them, and some games and features now check for them as well.
Secure Boot needs the board to be in its standard operating mode rather than a legacy compatibility mode. If the option looks locked, it is usually because of that mode setting, not a fault.
While you are in the settings, a BIOS update is worth doing on a brand new build. New boards often ship with firmware that predates later processor support and stability fixes. Download the latest version from the board manufacturer on another machine, put it on a USB stick, and use the board's built-in flash tool. Never do this during unstable power, and never interrupt it once it starts. If the board has a flashback feature that works without a processor installed, that is the safest version of the job.
What not to touch
BIOS exposes plenty of settings that can destabilise a build in one click: manual voltage controls, bus clocks, power limits, and per-core tuning. None of that is needed for a working gaming PC. Enabling the memory profile is the one performance setting worth changing, and everything else can wait until you have a specific reason.
Overclocking is a genuine hobby with genuine rewards, but it belongs after the build is proven stable, not during initial setup. Learn it on a machine that already works.
Save, exit, and install
When the defaults are loaded, hardware is detected, temperatures look sane, the memory profile is on, fan curves are sensible, and the boot order points at your installer, save and exit. The machine should restart into the Windows setup, and from there the build is a normal software job.
After Windows and drivers are in, it is worth returning to BIOS once more to confirm the memory profile survived and temperatures still look right under a quick stress test. A BIOS setup is not a chore you do once and forget. It is a five-minute check-in whenever something about the machine changes.
Get this stage right and the rest of the build behaves exactly as expected. That is the whole point of the settings: not to impress anyone, but to make sure the hardware you paid for is actually doing its job.