Most people install Windows and never touch their BIOS again. That’s a mistake. A stock BIOS with default settings often leaves significant performance and stability improvements unclaimed. This guide covers the settings that actually matter for gaming, ranked from highest to lowest impact.

Before You Start

Enter your UEFI by pressing Delete, F2, or F10 during POST (the screen right after power-on). Which key it is depends on your motherboard brand:

ASUS / ASRock: Delete
MSI: Delete
Gigabyte: Delete or F2
Intel NUC / some laptops: F2

If you miss it, just reboot and try again. Once inside, switch to Advanced Mode (usually F7 or a button in the corner) so you can see all settings.

1. Enable XMP / EXPO (Highest Impact)

RAM ships running at its base JEDEC speed — typically 2133 or 2400 MHz — regardless of what the box says. XMP (Intel) or EXPO (AMD) is a profile stored on the RAM stick that tells the BIOS to run it at its rated speed.

Location: AI Tweaker / OC Tweaker / Extreme Tweaker → XMP or EXPO Profile

Set it to Profile 1 (or the highest rated profile). Save and reboot.

Impact: Depending on your CPU and RAM, this alone can improve minimum frame rates by 10–25% in CPU-bound scenarios. It’s the single most impactful BIOS change most users haven’t made.

2. Enable Resizable BAR / Above 4G Decoding

As covered in our dedicated ReBAR guide, this allows the CPU to access all GPU VRAM simultaneously via PCIe.

Location (two settings, both needed):

Advanced > PCI Subsystem Settings → Above 4G Decoding: Enabled
Same section → Resizable BAR Support: Auto

Impact: 3–12% in supported games, zero cost, reversible.

3. Set the Correct Power Plan at BIOS Level

Many boards include CPU Power Management settings that override Windows power plans. Look for:

Location: Advanced > CPU Configuration or AI Tweaker

Enhanced Intel SpeedStep (EIST): Leave Enabled — disabling it locks the CPU at max clocks which wastes power and increases heat without gaming benefit
Intel Turbo Boost / AMD Precision Boost: Leave Enabled — this is your burst performance
Power Limit (PL1 / PL2): On Intel systems, increasing PL1 to match PL2 prevents the CPU from throttling after the boost window. Set Long Duration Power Limit to match your cooler’s TDP rating

Impact: Prevents CPU throttling under sustained load, which is common in long gaming sessions.

4. Configure C-States Appropriately

C-States are CPU sleep states that save power when cores are idle. The debate around disabling them for gaming is nuanced:

C-States Enabled (default): Best for general use. Modern CPUs exit C-States in microseconds. Leaving them on reduces heat and power draw.
C-States Disabled: Useful if you experience micro-stutters caused by cores waking from deep sleep. Try this only if you have reproducible stuttering that other fixes haven’t resolved.

Location: Advanced > CPU Configuration → C States or Global C-state Control

For most setups, leave C-States enabled and only disable them as a troubleshooting step.

5. Enable Fast Boot (With Caution)

Location: Boot > Fast Boot → Enabled

Fast Boot skips POST hardware checks and speeds up the boot-to-Windows time by 3–8 seconds. It’s safe for day-to-day use. The caveat: if you need to enter BIOS again, you may need to use Windows recovery options (Settings > System > Recovery > Advanced Startup) rather than pressing Delete at boot, since POST is skipped.

6. Set PCIe to Gen 4 or Gen 5

Some boards default GPU or NVMe slots to Gen 3 even when the hardware supports Gen 4 or Gen 5.

Location: Advanced > PCIe Configuration → PCIe Speed

Set the slot your GPU and primary NVMe use to Auto or Gen 4 (or Gen 5 if your board and drive support it). Mismatched PCIe generations can reduce NVMe throughput by 50% or more.

Impact: Critical for NVMe performance. Minimal GPU impact but costs nothing to correct.

7. Disable CSM (Compatibility Support Module)

CSM enables legacy BIOS boot mode for older operating systems. On a modern Windows 11 system booting from a GPT/UEFI drive, CSM should be off.

Location: Boot > CSM → Disabled

With CSM disabled, your GPU will use GOP (Graphics Output Protocol) instead of legacy VBIOS, which enables faster POST, proper UEFI boot, and is required for some features like Resizable BAR on certain boards.

Warning: Disabling CSM on a system that’s currently booting in Legacy/MBR mode will make Windows unbootable. Confirm your Windows installation is UEFI-based first: run msinfo32 → look for BIOS Mode: UEFI.

8. Enable Virtualization (If You Use VMs or Anti-Cheat)

Location: Advanced > CPU Configuration → Intel VT-x or AMD SVM Mode

Some anti-cheat systems and virtualization software require this to be enabled. It has no performance impact on gaming itself but causes issues when disabled.

9. Fan Curve Optimization

Location: Hardware Monitor / Q-Fan Control / Smart Fan

Default fan curves are often conservative (quiet) or aggressive (loud). For gaming, set a curve that keeps CPU temps below 85°C under load without running fans at 100% constantly:

0–40°C: 30% fan speed
40–60°C: 40–50%
60–75°C: 65–75%
75°C+: 90–100%

Good thermal management directly affects sustained boost clocks on both Intel and AMD CPUs.

10. Disable Unused Onboard Devices

Location: Advanced > Onboard Devices Configuration

If you don’t use onboard audio (using a DAC or sound card instead), Bluetooth, or the secondary NIC, disabling them frees up a small number of IRQ resources and slightly reduces background interrupt load. The impact is marginal on modern systems but costs nothing.

BIOS Settings Quick Reference

Setting	Recommended Value	Impact
XMP / EXPO	Profile 1	High
Above 4G Decoding	Enabled	High
Resizable BAR	Auto/Enabled	Medium
PCIe Speed	Auto/Gen 4	Medium
CSM	Disabled	Medium
C-States	Enabled (default)	Low
Fast Boot	Enabled	Low
CPU Turbo Boost	Enabled	High
Virtualization	Enabled	Low

Conclusion

The BIOS is where your hardware’s baseline behavior is set. Many systems ship with XMP disabled, PCIe running at the wrong generation, and ReBAR off — all problems solvable in five minutes of BIOS time. Tackle these settings in order of impact, test stability after each change, and you’ll have a fundamentally better-tuned gaming PC without spending a dollar.