Keyboard ghosting and rollover: what your test really shows
When several keys are held together, the important question is not only “does each key work?” but “does this exact combination still reach the computer?”
Rollover is about simultaneous inputs
A keyboard can register every key perfectly when pressed alone and still behave differently when several keys are held together. Rollover describes how many simultaneous presses can be reported, but the practical limit can depend on the exact combination. That is why a real combination you use in a game or shortcut can be more informative than a label on the box.
Ghosting, blocking and browser interception are different
People often call every missing multi-key input “ghosting.” In practice, a combination can fail because the keyboard matrix blocks it, because firmware chooses not to report it, or because the operating system/browser reserves part of the shortcut. A browser tool sees only the final key events delivered to the page. It cannot see the electrical matrix directly.
How to test a suspicious combination
- Use ordinary letters or number keys first, not OS shortcuts.
- Hold the combination instead of tapping keys one after another.
- Repeat it three times and note whether the same key is consistently absent.
- Try the same keyboard in another browser or computer if the result matters.
- Compare with the keyboard maker's own rollover or diagnostic documentation.
What a good browser result means
If all held keys appear simultaneously, you know that particular combination reached the browser on this setup. You have not proven every possible combination, every USB report or a universal “N-key rollover” specification. BenchRush therefore reports the maximum seen in your run and the actual held keys instead of issuing a hardware certification.
Single-key problem?
If one key is missing even when pressed alone, start with the regular keyboard test. A rollover test is most useful after individual keys already work.