I put 14 LEDs on each strip on the 24" fixture. So u should be able to get around 20 LEDs per strip. 40 LEDs should put out some decent light. I'm running these LEDs at 700mah, so they run cooler. If u bump it up and run them at 1000, u might need some additional cooling. The way it's setup now though, the stock ATI fans works great, and LEDs are kept reasonably cool
