do you think this would be ok to run? or really pushing it?
I just ran into a problem where I could not get 4 sapphire 7950’s to work on a 850 PSU. These cards according to online sources pull about 225w each!
what happened when u tried to get it to work? did it just not power on? or?
It would boot, then as soon as mining started it would either shut off, sometimes it would blue screen and restart. Also, i had a 850w psu and a 650w psu going to one of the cards to try and help with power but it might be causing more problems.
dunno wether its worth me risking buying the 3rd or not 
honestly, just buy the #1 psu everyone is buying. The EVGA 1300 G2. It may be overkill for 3 cards but it’s guarantee to work and you can be worry free if you add another 2
I’m running (4) 7950s using Claymore 6 miner (4 intensity). Power at the wall, depending on what the fans are doing, runs around 690 - 720.
Even if it had enough watts you would run out of PCIe connectors for the 3 GPUs