Does undervolting LED fans cause dimming?

knadams · March 25, 2015

Hey guys, I'm looking into getting some green LED fans like these Cougar fans (non-PWM) and controlling them with an ASUS x99-a mobo using the built in DC voltage regulation. I was just wondering what effect if any this would have on the LED's themselves when the fans are not getting the full 12 volts. Will the fans dim? Will they just switch off? I'd like to know what you guys think, especially if you have some experience with this particular issue.

AlwaysFSX · March 25, 2015

Yes, I have an LED fan on my controller and it's noticeably dimmer at medium or low settings because it's not running at 12V.

Liam-McShane · March 25, 2015

Yeah they go dim. Some fan controllers will make them flash as they mimic PWM but a motherboard will just dim them.

knadams · March 25, 2015

Thanks guys. I actually think this will be a cool effect when I have the fans set up on profiles to increase speed with increased temps. So my rig will be dim at idle and get brighter under heavy loads.