Ok, let's hear it!

[sphelps]

Originally Posted by mrhasan

Heat sinks are meant to be hot. They taken the heat from the LEDs and dissipate them to the air but not at a rate which makes it run cool (heatsinks have a maximum heat capacity and stays below that or else the heat sink is not the right one for the system). Don't know why yours run cool Probably you are using oversized heat sink?

Ahhh..... wrong

LEDs produce a large amount of heat per area which can seem high because of there size but overall is very little. The junction temperature (between LED and heat sink) needs to be kept relatively cool to insure the LEDs don't overheat, in order to do this the heat sink has to be large enough and kept cool enough to maintain allowable LED temperatures. The cooler the heatsink the better the LEDs work and the longer they last. Most heat sinks probably run around 25-30°C.