I don't expect the fans have much of a difference lol, in comparison to the GPUs/drives. I think if you were at that kind of load though, it's probably not safe to run a 1200W PSU?
YOUR BASKET
1 x
Corsair AX1500i Digital ATX 80 Plus Titanium Modular Power Supply (CP-9020057-UK) £329.99
1 x
EVGA SuperNova G2 1300W '80 Plus Gold' Modular Power Supply (120-G2-1300-XR) £169.99
Total : £514.08 (includes shipping : £11.75).
The thing is, the 1500W PSU is veeeery expensive compared to 1300W units
Doing a PSU calculator test, it shows 1013W at 90% load?!

either way, stonedpenguin's tests show differently, so probably best to go with a 1300W + PSU OR go for two PSU's if possible?
I believe the Antec PSU's have a connect function thing so two PSU's can work together