It's not subbing because I don't have either yet; I just know what the Primo can accommodate and I'm wondering which would be a better overall solution. Also, this is just for bottom intakes, not front intakes or the case as a whole.
And yes you're right. It's for an R9 290 crossfire configuration and the heat being generated is way more than my current case config can handle
However, do this mathL
Take your 2 x 140 mm fans, compare the CFM they can move with the rated CFM (cubic feet per minute) of the 4 x 120 mm fans. That should tell you which solution is the most efficient at moving air.
So in my scenario, I'd be using Corsair AF140 Quiet Edition fans OR Corsair SP120 fans. Both the SP120 Quiet Editions and Performance Editions move more air than the 2x Corsair AF140's but what about noise? How could I accurately calculate maximum noise output for each setup? Individually, it's clear which fans are quieter but when you put four together.. To just 'stack' the dBA would be incorrect wouldn't it?