I don't know why many comments are so rude in this thread, if you aren't going to be of help whey even bother to reply in the first place? There is actually a way to turn off GPU LEDs I've tried this on a 3070 ti using hive OS, the menu looks like this
This method does not work with all video cards, this is the main problem. On some graphics cards in the farm, the backlight will work, so miners have to use Double-sided, marker or insulating tape.