SP120 looks to have just hub mounted LEDs. It doesn’t say on Corsair’s site but from the pictures I would guess 4 LEDs per fan. I have ML140 RGB fans in one of my builds and they also have hub mounted LEDs, 4 per fan. You can experiment with changing one LED at a time to see when you no longer see any effect from changing them and figure out the number of LEDs that way as well.