Is it okay to run a power supply up to it's maximum output voltage?

5 Cree XR-E LED's Buckpuck
5 * 3.3 + 2 = 18.5v

Power supply = 19v 3.42a

Will this cause a lot of heat?

have you actually tested the output of your PS.. ALSO what current are you running your led's at.. usually each led draws around 3.6v at full power.. so that could cause some problems for you..

I don't currently have the tools I need to test the output of my power supply, and the LED's would be wired to a 700mA buckpuck but I wouldn't be running them at full power. Probably more like 60% power. So what I'm kind of gathering is that I need to test my power supply and then make sure it has a little higher output than what I want to power?

well its good to have a bit of headway.. you could still be looking at higher V than3.3 AT 700mA so it would be better to aim a little higher in the supplied voltage IMO..

Agreed. It's just a little too tight of a margin to be comfortable. You should go out and pick up a multimeter. It's a must for doing any work with electronics. How would you verify that you had no shorts to the heatsink before you fire it up for the first time?

Thanks guys, I will drop down to 4 LED's and a buckpuck for my power supply then and look into a multimeter next time I am out at home depot