Know your BIOS settings (the 5 that matter)

Steps

1. 01

   Set up a way back before you change anything

   • Photograph every UEFI screen you are going to touch — there is no undo in here
   • 'Load optimised defaults' discards settings you wanted to keep too, so those photos are your only record
   • Find your board's CMOS-clear method now, while the PC still boots: it is a jumper or button on the motherboard — look for CLR_CMOS or similar in your board's manual — or removing the coin battery for a minute with the PC off at the wall
   • Change one setting, then reboot, before changing the next

   !Careful: This is the one step you cannot skip. If a change stops the PC posting, UEFI is no longer reachable — clearing the CMOS is then the only way back in, and it resets every other setting with it.

   Why?

   Changing five things at once and getting a PC that won't start tells you nothing about which one did it. One at a time is slower and it is the difference between a five-minute fix and an afternoon.

2. 02

   Get into UEFI

   • Press the setup key repeatedly as the PC powers on — usually Delete or F2, though some laptops use F1, F10 or Esc
   • The key is normally named on the first screen as the PC starts, and always in the manual
   • Easier and more reliable from Windows:Settings›System›Recovery›Advanced startup›Restart now›Troubleshoot›Advanced options›UEFI Firmware Settings›Restart

   ✓You should see: The firmware setup screen, usually with a simple mode and an advanced mode — the settings below mostly live in the advanced one.

   Why?

   The Windows route avoids the timing game entirely, and it is the only reliable way in on a PC with fast boot enabled.

3. 03

   Turn on the memory profile (XMP on Intel, EXPO on AMD)

   • Find the memory profile setting and switch it from Auto or Disabled to Profile 1
   • Boards put it on their overclocking or tweaking page under a name like XMP, EXPO or D.O.C.P — your board's manual names the page; it is not in the same place on every board
   • Save and exit, let the PC boot, then check Task Manager → Performance → Memory and confirm the Speed matches what the kit was sold as

   ✓You should see: Memory Speed in Task Manager matches the rating on the box — not the speed memory falls back to until a profile is enabled, which is typically 2133 or 2400 MHz for DDR4 and 4800 MHz for DDR5.

   !Careful: A memory profile is an overclock, just one the manufacturer pre-tested. Not every kit reaches its rated speed on every board. If the PC becomes unstable — random restarts, crashes under load, failures hours later — this is the first setting to turn back off.

   Also see: Upgrade your RAM (and match it)

4. 04

   Turn on Resizable BAR for the graphics card

   • Enable both 'Above 4G Decoding' and 'Re-Size BAR Support'
   • Above 4G Decoding commonly has to go on first before the other option appears at all, and boards label both slightly differently — read the labels rather than hunting for exact wording
   • Check it took effect afterwards in your graphics driver's control panel: NVIDIA reports Resizable BAR in its system information, and AMD's equivalent is named Smart Access Memory

   Why?

   Resizable BAR lets the CPU address the whole of the graphics card's memory at once instead of in small windows. The gain is real but modest and game-dependent — a few per cent, not a transformation.

5. 05

   Boot order, virtualisation and C-States

   • Boot order: put the drive Windows is installed on first, so the PC stops searching other devices at every start
   • Virtualisation: enable it only if you run virtual machines, Android emulators, WSL or Docker — it is called VT-x (or sometimes VMX) on Intel and SVM on AMD
   • C-States: these let the CPU drop into low-power states when idle. Leave them on unless you do latency-sensitive work and have measured a problem — turning them off raises idle power and heat for no everyday benefit

   !Careful: Don't disable C-States on a laptop. They are a large part of how it reaches its rated battery life.