number of fans question

hello, i have recently started my computer build and have decided to buy fans next. the case i have (cooler master elite 430) has slots for 6 fans. i already have one 120mm installed with 3 more 120mm on the way and 1 140mm fan also on the way. if you're counting, you've noticed that I've left one out. the last slot is on the bottom of the case, right in front of the psu. my psu interferes with a 120mm fan being installed, so i have to go with 90mm or 80mm. my big question is, would i really need that extra 90mm or 80mm fan in order to run a cool system. sure, it'd make my system cooler, but would it make such a huge difference with all my other fans already installed that i would need to get a 90mm or 80mm fan for the bottom? thanks in advance for your help

With all the other fans in the case, I don't think you will need a fan in that position, especially since you would have to rig up something to work there due to the psu interfering with a normal install of a 120 mm fan there.

Most cases are anemic with the intakes, huh? It would be nice to have an intake on the bottom to feed the hot video card(s), if you have them. Otherwise I wouldn't add one if you're not overheating.