That light isn't devoid of warmth. You can't make that much light without some heat but it's less then half of what a 600 watt hps puts out. Plus that is the xl model. It has a 50% larger heatsink then the 260's I own. It should run pretty darn cool and be almost nothing if you put a fan on the heatsink. I'm able to run both my 260's and 4 qb120 boards in my 4x8 right now with my exhaust fan on low. It's 73 degrees in there. I can't even get it warm in winter. Im hoping it will hit 80 when I section it in half for flower.
With led that is my target temp. With HPS 75-78 is better. The qb260xl is a very cool running light. I'm actually going to go look at a couple tonight. My buddy replaced two 600 watt hps with 2 x qb260xl's and he wanted me to come by and check out his setup tonight. I can report back on how hot they run but I already know they will be no problem to cool.
Optimal temp under these leds seems to be around 80-82. 84-86 is where they start to suffer. My buddies qb260's that he replaced his 600hps's with runs so cool compared to the HPS lights he has his exhaust fan on low now on a thermostat so that is doesn't get too cold. I checked on it last night. He has a fogponic setup. The roots are crazy.