Myth: setting SystemResponsiveness to 0 gives games 100% of the CPU

Myth: setting SystemResponsiveness to 0 gives games 100% of the CPU — via Microsoft Learn

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A popular gaming tweak sets SystemResponsiveness to 0 under the Multimedia SystemProfile key. Microsoft's documentation says values below 10 are clamped to 20, so 0 behaves the same as the default of 20. It does nothing for frame rates.

What to do instead

If you already changed it, set it back to the default: HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile → SystemResponsiveness (DWORD) = 20.
For real gains, update GPU drivers, turn on Game Mode (Settings → Gaming → Game Mode) and close background apps you don't need.

The value is the percentage of CPU reserved for low-priority tasks by the Multimedia Class Scheduler Service (MMCSS). Values not divisible by 10 are rounded down; values below 10 or above 100 are clamped to 20; 100 disables MMCSS altogether. MMCSS only affects threads that register with it (mainly audio and media apps), not games in general.

Sources

Multimedia Class Scheduler Service — by Microsoft Learn

Source reviewed: 2026-11-02
Link checked: 2026-11-02
Tested hands-on: Not by Oddbyte.Me

Oddbyte.Me hasn't tried this on every Windows build, so keep the undo handy.

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Myth: setting SystemResponsiveness to 0 gives games 100% of the CPU — via Microsoft Learn

What to do instead

Sources

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