MSI B760M Mortar BIOS Quiet Guide

MSI B760M Mortar BIOS Quiet Guide | Generated by AI

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Here’s the detailed walkthrough for your MSI MAG B760M Mortar BIOS:

🛠 How to Fix: Step-by-Step BIOS Guide

1. Enter BIOS

Restart your PC
Repeatedly press Del (Delete) key immediately when the MSI logo appears
Or press F2 if Del doesn’t work

2. Set AIO_PUMP to 100% Fixed Speed

- Press F7 to switch to Advanced Mode (if you're in EZ Mode)
- Go to: Hardware Monitor (or Settings → Hardware Monitor)
- Find: PUMP_FAN (or AIO_PUMP header entry)
- Set: DC Mode (not PWM)
- Set temperature source: CPU
- Set the fan curve to a flat line:
    Drag all points to 100%
    Or manually set:
        0°C → 100%
        100°C → 100%
  This locks the pump at full speed always.

Why: The Thermalright Frozen Prism 240 pump should run at constant speed. Varying pump speed causes water flow changes → temperature oscillation → fan ramping noise.

3. Set CPU_FAN Custom Curve

- Stay in: Hardware Monitor
- Find: CPU_FAN (or FAN1)
- Set: PWM Mode (not DC)
- Temperature source: CPU
- Select: "Custom" or "User" curve (not "Smart Fan" default)

  Set these points:
       ┌──────────┬──────────┐
       │ Temp (°C) │ Duty (%) │
       ├──────────┼──────────┤
       │    30    │    30    │
       │    50    │    50    │
       │    70    │    75    │
       │    85    │    100   │
       └──────────┴──────────┘

  On MSI boards, you typically:
    - Select a point on the graph
    - Press +/- or type the value
    - Move to the next point

Why this curve matters:

Current (idle)	After fix
31% PWM → 1546 RPM	30% PWM at 30°C → ~550 RPM
CPU at 35°C, fan loud	CPU at 35°C, fan quiet

The Thermalright prism fans have a high minimum speed (~1000-1200 RPM minimum). So setting 30% at 30°C will likely get you ~1000-1200 RPM instead of the theoretical 550 RPM — but that’s still much quieter than 1546 RPM.

4. (Optional but Recommended) Undervolt + Power Limiting

BIOS path:
    Overclocking → Advanced CPU Configuration

Set:
    CPU Lite Load: Mode 5-7 (Mode 7 is more aggressive undervolt)
    → This reduces voltage = less heat = fans don't need to ramp

    Long Duration Power Limit (PL1): 200W
    Short Duration Power Limit (PL2): 200W
    Tau: 56 seconds or Auto
    → Limits max heat output without noticeable gaming performance loss

Expected improvement:

Setting	Cinebench R23	Max Temp	Noise
Default (253W)	~40000 pts	100°C	Loud
CPU Lite Load Mode 7 + 200W limit	~37000 pts	80-85°C	Quiet

5. Also Check Your HDD

You have a WD20EZBX 1.8TB (7200 RPM) mechanical hard drive at /mnt/data. This is a physical noise source separate from fans.

Quick test:

# Unmount to see if noise disappears
sudo umount /mnt/data
sudo hdparm -Y /dev/sda   # park the drive
# Listen — if noise stops, that's your HDD

6. Apply and Exit

Press F10 → Save Changes & Reset → Yes

After reboot, run ww linux check-fan again to verify fan1 RPM dropped.

Summary Checklist

Step	What	Expected Result
✅ 1	AIO_PUMP → 100% DC fixed	Stable water flow, no pump ramping
✅ 2	CPU_FAN → custom PWM curve	fan1 drops from 1546 to ~1000-1200 RPM at idle
✅ 3	CPU Lite Load Mode 7	Less voltage, lower temps
✅ 4	PL1/PL2 = 200W	Max heat capped, fans stay quieter under load
✅ 5	Check HDD noise	Eliminate mechanical noise confusion

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