Coolz202

I've been using the Corsair H115i PRO AIO for a little over a year now, and I've only just now noticed that the fan speeds are very slow from what I've seen other people having, my 2 fans are set to the 'Extreme' preset and reaching a maximum of ~875 RPM, but more realistically hovers around the 850 mark. Could anyone provide an explanation as to why this could be happening? Thank you!