Hi - how did you get the GeForce to work - I thought the Z840 only has 6 pin power and the GeForce needs an 8 pin?
I bought the Titan X (Pascal) and put it in my Z440. The Z440 has two six pin power cables just as the Z840 so i bought an adapter. So one six pin becomes an eight pin power cable. It works as ecpected and is cheap. No adapter is included with the card.
AFAIK it is possible to just use the two six pin power cable but i am not aware what the downside might be.
Image may be NSFW.
Clik here to view.
