GTX 970 ACX cooler question...

Hey guys - all of my previous and current GTX cards (275 to 680) have had the reference blower cooler because my rig is on air and I do not need that hot air inside from the GPU. How much does the ACX exhaust any of the GPU heat? I understand the new version of EVGA's ACX is supposed to be the best ever from any manufacturer.

I can't seem to find a definitive answer anywhere out there in general on the ACX cooler. And yes, I'm looking to get two 970s for SLI. FYI my case is a high-flowing Antec Nine Hundred (see sig info below). Any thoughts on which would be better overall for my rig? Thanks in advance!