Compatibility question: HP Z4 G5 Workstation and GeForce RTX 4080 Super

[appdic]

Hi,

I have found this topic: https://h30434.www3.hp.com/t5/Business-PCs-Workstations-and-Point-of-Sale-Systems/HP-Z4-G4-RTX4080-F...

I would like to connect the graphics card to an HP Z4 G5 Workstation with a 700W power supply. However, the power supply only has 2 x 8-pin PCI-e ports instead of 3 x 8-pin PCI-e ports available for 12 Volt High Power (12VHPWR).

Can someone tell me if 3 x 8-pin PCI-e ports are absolutely necessary? Do additional fans need to be purchased for the graphics card?

[SDH]

Please use this forum's search feature to look for something like "PCIe supplemental power cables". This issue has been posted about numerous times here, related to the higher than ATX standards power capacity carried by the HP supplemental power cables that are 6-wire, and the specially engineered power adapters that HP makes to convert their 6-pin plugs to full power 8-pin plugs. The HP cables are rated to 18A each. I would not buy anything but the best for this purpose, engineered to carry the higher wattage load you'd be running through them. HP knows the engineering so that is only what I'd use. Nothing that money can't fix...

However, that does not get you to the nVidia recommended power supply specifications given your "700W" power supply, below the 750W minimum value they specify. You could look into a replacement higher power HP power supply and see what the max is and if it provides 2 or 3 of those cables. You might need 3 of the special HP 6-to-8 adapters too but I recall that if you feed enough power in via 2 you may not need to populate the third 8-hole socket. 18A x 12VDC x 2 + 75W from the PCIe slot the card is inserted into should be enough.

nVidia official specs...

EDIT:  The information you provided regarding the max TDP wattage your power supply is rated for is low... you might have enough with your current 775W power supply.  Below is from the HP QuickSpecs for the Z4 G5, released 17 days ago, but on added review this is the way those workstations have been from the beginning. The 1125W version could be worth considering rather than pushing towards the top limit of what you currently have. Something tells me you are beyond a full power user:

I'd still want the higher max TDP power supply...

[SDH]

Back to your second question... yes, added cooling will be needed. There is a bottom front case cooling fan that you may already have. There is a unique very bottom flat long dual-fan cooling device for the PCIe slots area from below. I'll include a picture of the Z4 G5 case bottom so you can see the new perforations down there to allow good air flow through the optional bottom flat dual-fan active cooling device, and also a pic of the left side case cover with its new perforations there too:

More cooling...Case bottom with perforations...Case cover with perforations...

A good HP PDF to have:

HERE 

The bottom flat dual-fan cooler is not really a "PCIe Card Retainer" device. It is inserted over the case perforations there and pulls in cooling air from below. The case cover side perforations provide the preferential venting direction. This active cooler is demanded by the motherboard not just if there are two PCIe graphics cards... it also detects high current into the graphics subsystem, and that will be your situation:

HERE 

HERE (Review this one for sure...)