Upgraded GTX 660Ti to GTX 970 oc

Hello everybody,

I got problems after GTX 970 installing in my Yosemite 10.10.5 (with chimera boot loader).

My system is laggiest than previously (my mouse lag on my desktop !!), only DVI display works and when do "About this Mac" > I see "Graphism Monitor 5mo"

So my new GPU isn't recognize

Anybody know my problem and the solution ?

My configuration :
i7-3770k
16 Go Ram
MSI ZH77A-G43
KFA2 GTX 970 Black Sniper Edition EXOC
2 display : 1 DVI, 1 display port

ps : Sorry for my bad...

Upgraded GTX 660Ti to GTX 970 oc