Second GPU not working

[ArM2991]

I have a gtx 760 mars which is a dual gpu card with 2 760 gpus. The problem is that i cannot use 2 gpus at the same time. I disable the second gpu in nvidia control panel and every game works just fine. The problem starts when i select ''maximize 3d performance'' which would enable 2 gpus, no problem with that until i jump into a game or a benchmarking program, i got a black screen with an error message ''[app name] stopped working'' In my opinion, i think my powersupply is not powerful enough for the card.
i7 5820K
Asus rampage v extreme
Corsair cx750m power supply
16 GB DDR4 ram
corsair h100i cpu cooler
Asus GTX 760 Mars
Sorry for any mistake as this is my first time on this forum
And English isn't my primary language

 

[Dazinek]

Make sure you have the latest nvidia drivers, I understand that the 760 Mars has some bad driver support.