Well it's a little hard without grow room dimemsions, light size and stuff, but ill tell you what I did when I had major over heating issues in a small grow room with a 400 HPS.
I had similar setup, 1 x 4inch intake fans and 1 x 4 intake exhaust fan. Basically I decide too hook up both fans as exhaust and let the intakes just be a passive intake ( no fans just holes)
This worked great for me, moving more out air gave the heat a less chance to stagnate and build up. Using passive verse active intakes is a highly arguable topic on RIU so im just saying what worked for me
I'd only use a active intake if i was trying to move fresh cool air in from a fair distance away.
Just my 2 cents.