Question Graphics card upgrade for HP Z600 ?

[Xeon z600]

I have an HP Z600 with Xeon CPU and I want to upgrade my graphics card. Which card suits best for Xeon ? Currently I have Quadro 4000 which is not good for games.
I want to use my PC for both work and games. Plzz guide

 

[rgd1101]

what the pcie power cable does that psu have? that a kind of old system

 

[Xeon z600]

what the pcie power cable does that psu have? that a kind of old system

Slots one, two, and four are PCIe GEN2 slots. Slots one, three, five, and six use open-ended PCIe connectors, so a PCIe x16 card can be inserted. This allows the workstation to support more PCIe x16 expansion cards.

https://pin.it/2ihoeHj

 

[rgd1101]

I mean from the psu(power supply)