I The top of my cab is about 10 degres cooler than the bottom . That just seems ass backwards to me because heat rises. Cant wait to get those desk fans.
You need to direct the airflow better. Coming from a PC builder here, You cant just blow some fans up on a MH light and expect it to cool down, you need good proportional airflow, it doesnt even need to be blowing on the light itself, just need air coming into the grow box clean, and back out without any shit in the way. Here lemme draw you a picture.
Is this what your grow box looks like? Im guessing yes, Great
IN THIS PICTURE... as you can see, have the fans blowing on your plants,, this will act as a heat reducer, and it will also keep them strong....
SEE THAT VENT ON TOP? YOU REALLY REALLY NEED THAT, OR heat will be up in your box. If that Light in CREATING THAT MUCH HEAT, then it needs to come out of the closet, because thats your problemo.