2x 360 rads vs 1x 360 rad and 1x 240 rad for crossfire 290's?

[Wowbowty]

I plan on using 2x 290's for my future and was wondering what will a be sufficient amount of cooling.

 

[mrmez]

With a quality rad and fans, an internally mounted 360mm should be plenty for 2 cards and a cpu.
I've got a very good externally mounted 120mm rad with a single fan that used to cool both OC'd cpu and gpu just fine.

You could get creative with a 240 and run 3-4 fans in pull config with a shroud. Always use dust filters on the rads too, will save you from having to get in there with a blower or vac in 6 months.