I'm not 100% but I have been running a 50mm on the cooler for a week now with no problems. Getting some nice results bridging with it too. Just a regular 50 not a blower type. I think jetguy said something to the effect of the board being capable of handling more fans. I have two noctua's 40mm fans coming, I have been threw 3 fans already. The radio shack 40mm I got is a nice fan, but it suffered the wrath of my thumb.