the heatsink fans combo was to small for cob so I used flat diamond plate aluminum and but computer fans above it and cobs just nerves about temp, for now, I put a big fan on the side blowing on cobs to help out the little fans im going to make a order for more cobs and driver, and stuff also I will add 4 extra passive heatsinks on this order and redo set up and run passive to all cobs, don't like the idea if fans stop working I could burn up my cobs. I have a miniature tornado in my grow space now and looks ghetto as shit don't like it but will have to do until order arrives changing over to cobs getting the hps out thanks for the info ihearall