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I need advice: I plan to use a heat-sink for cooling 2x 80W white LEDs over my friend's tank. The heat-sink is a "pin fin" design, 6 inches by 6 inches which combined with active cooling should dissipate more heat than other fin designs. Here it is:

enter image description here

Ebay Link

Now, I plan to attach 4x 12-volt fans on top for strong active cooling. My question is would such a system cool 2x 80W warm white LED chips effectively? I know LEDs aren't very efficient, and only a percentage will be actual heat produced, a few degrees above operating temp is no bother for us, so bearing all this in mind is this 4 FAN "pin fin" heat-sink idea feasible enough to effectively cool both 80W chips?.

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  • \$\begingroup\$ Try asking for the manufacturer's datasheet for the heatsink. The vendor appears to have decent documentation for other parts, so it's worth a shot. That will help put any numbers in answers into context. \$\endgroup\$ – W5VO Feb 7 '14 at 22:20
  • \$\begingroup\$ This question came from the gardening SE? What? You can plant these? \$\endgroup\$ – JYelton Feb 7 '14 at 22:27
  • \$\begingroup\$ Also, why do you say "LEDs aren't very efficient?" They're among the most efficient light sources available; unless of course you mean as a heat source... \$\endgroup\$ – JYelton Feb 7 '14 at 22:34
  • \$\begingroup\$ @JYelton: Heh. I'm pretty sure the LEDs are going to be used as a light source for plants. \$\endgroup\$ – Ignacio Vazquez-Abrams Feb 7 '14 at 23:11
  • \$\begingroup\$ @Ignacio I agree; but when I first saw the image of a heatsink and the migration notice, I was taken by surprise. :) \$\endgroup\$ – JYelton Feb 7 '14 at 23:13
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What is the thermal resistance of the heatsink - hint usually stated in degC per watt.

I couldn't see it in the link but it might be in the order of 0.25degC per watt and if so it will warm up maybe 40 degC if all the power is converted to heat. You must find out how efficient the LEDs are - I suspect a ballpark figure of 20% and this means 128 watts are dissipated as heat.

Again if the heatsink is 0.25degC per watt then it will warm up to 32degC above ambient.

The effect of the fans could be good enough to halve or quarter this temperature rise. If you are lucky the heatsink may only rise 8degC.

I realize I've taken some guesses to to give an answer but at least the OP is aware of the process.

I'll say one more thing - the type of heatsink you've chosen is the best design I've come across for thermal heat dissipation - I've used a similar type for power transistors with 4 fans and it was awesome in getting rid of that pesky heat.

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