Upgrading an old Hackintosh [part 2]

A few weeks ago I asked for help repairing/upgrading my dead Hackintosh and was recommended an AMD RX560 graphics card, because the GT240 I've got won't be powerful enough for a modern version of OSX.

I can't get the new graphics card to work. When it's in,the fan spins, but there is no signal on either the HDMI, or the DVI ports. Putting the GT240 back in works fine.

Is there something I've missed about installing this card, beyond putting it in the slot and putting the screw in? The manual mentions plugging some six-or-eight pin power, but there are neither sockets on the card, nor cables on the PSU as described.

Is it knackered?

Thanks.