GTX 980 ti SLI

[VK30061H]

HI, Just a quick question. Going to get a couple 980 ti's for SLI, wondering what would be better. 2x Reference cards or 2x ACX 2.0, Twin Frozr cards for best performance / cooling?
Case: Fractal Design R5 (HDD cage removed, 2x 140's front intake)
MB: MSI Z97 Gaming-5

Thanks.

 

[Sergeant_Sneaky]

For SLI, reference is better as the heat is pushed out the back of the case instead of recycled into the case, they can be quite loud though.