Q&A

What is N-key rollover?

N-key rollover (NKRO) means the keyboard can detect and report every key that is pressed at the same time, in order — no key signals are dropped or conflicting.

1. Why do key conflicts happen?

Traditional keyboards (especially cheap or older models) are limited by their key-matrix circuit. When several keys are held at once, the circuit may fail to determine each key's state correctly, which leads to:

• Dropped keys: you press 4 keys and only 3 are reported.
• Ghost keys: a key you never pressed is reported anyway.

For example, on an old keyboard, holding A, S, D, F together might make F do nothing — or produce a phantom Q.

2. Rollover levels

Type	Description	Typical use
6-key rollover (6KRO)	Up to 6 keys at once (including modifiers such as Ctrl, Shift)	Most office keyboards, ordinary USB keyboards
N-key rollover (NKRO)	All keys at once, theoretically 100+	Gaming keyboards, mechanical keyboards, high-end keyboards

3. What is it good for?

• Gaming: fighting games (combos), rhythm games (many keys at once), FPS (Shift+W+Space+mouse at the same time) need every key recognised precisely.
• Fast typing / key combos: avoids mis-detected shortcuts.
• Shared or special input: e.g. two people playing on the same keyboard.

4. Things to note

• Most modern mechanical keyboards support NKRO by default (or can switch back to 6KRO with a shortcut, for compatibility with old BIOS or certain programs).
• NKRO works over USB; a handful of very old mainboards or systems may need PS/2 for full rollover (rare).
• Enabling NKRO won't damage the keyboard. If you run into compatibility issues (some games, remote-desktop input), switch back to 6KRO.

To check whether your keyboard is currently in NKRO mode, use an online keyboard test tool (e.g. "Keyboard Test Utility" or Microsoft's keyboard test) and hold several keys at once to see whether all of them register.