OK, my opinion is to place your box in a room with an ambient temperatur of no more than 65 degrees. Second, you don't need an intake fan, just a couple smaller holes, mayber 5cmX2cm ( you don't want the total size of all 4 holes to be any more than 1/4 the size of the extraction hole) one on each side of the box at the very bottom of the box. I put some sort of covering over them so air can get through, but light can't. I like to cut up the black furnace filters and tape them over the holes.
Next, you want a GOOD fan extracting air from the top of the box. Don't be afraid to use a failry strong CFM fam, even into the 200. Doing it this way, you will creat a negative pressure situation in the box, basically sucking air in from the lower holes at 65 degrees, and the sucking air out at a very high rate through the canopy fan. Doing it like this, it will be very hard for the temps to get much higher than 75.
In a box this small, there is no reason for an intake fan, it can actually be detrimental. As long as your outake fan is srtong enough, you will be fine with a couple passive intake vents at the bottom.