Is the reactive lighting setting on keyboard and mice viable for testing input lag?

[LLm1]

I was wondering if setting the keyboard or mouse with RGB to reactive lighting (lights up when clicked) is viable for testing input lag with a high speed camera opposed to using a modified mouse with an led soldered to the left click.

To clarify to people who don't know what I'm talking about; you record the game with a high speed camera and trigger an action with a key out mouse button rigged to an led, and count the number of frames between the led lighting up and the action occuring on screen giving you the click latency.

My main concern is whether or not the led on the reactive setting is in sync with the click, or if there's a delay in between.

[jorimt]

I was wondering if setting the keyboard or mouse with RGB to reactive lighting (lights up when clicked) is viable for testing input lag with a high speed camera opposed to using a modified mouse with an led soldered to the left click.

Short answer is: don't bother. Long answer is: sort of, but it becomes highly involved and tedious to get any usable, reliable data.

My main concern is whether or not the led on the reactive setting is in sync with the click, or if there's a delay in between.

There is a delay, and it is usually variable. It can also depend on the device. My general impression is keyboard is worse in this respect.

[MT_]

Not sure, most leds on peripheral devices don't switch at 1ms iirc.

I wouldn't rely on it.