Maybe if you try a card that's more closer related to a officially supported card.

These are the cards officially supported by HP

NVIDIA Quadro NVS 295 256MB PCIe Graphics Card
NVIDIA NVS 300 512MB Graphics
NVIDIA Quadro NVS 450 512MB Graphics
NVIDIA Quadro 400 512MB Graphics
NVIDIA Quadro 600 1GB Graphics
AMD FirePro V3900 1GB Graphics
AMD FirePro V4900 1GB Graphics
NVIDIA Quadro 2000 1GB Graphics
NVIDIA Quadro 2000D (Spec DVI only card)
AMD FirePro V5900 2GB Graphics
AMD FirePro V7900 2GB Graphics
NVIDIA Quadro 4000 2GB Graphics
NVIDIA Quadro 5000 2.5GB Graphics

Looking at Nvidia's in the list they are all Fermi based, so would limit myself to this.
If you want to take even less risk and we use the Quadro 2000 as an example (as it also has 1GB) something based on the GF106 processor
https://www.techpowerup.com/gpu-specs/nvidia-gf106.g83

The maintenance and service guide also says on P91 that the original 475W PSU can handle a total of 150 watt card (or two 75 watt cards) it seems at one point HP upgraded with a 600W PSU in which case the new maximum was a 250 watt card.
https://jp.ext.hp.com/lib/doc/manual/workstat … /504630_001.pdf

😳

Thank you very much chinny22 for your help.
This info is very usefully.

The original idea was to use this card because I have one (installed in other more slow PC).
But now I have a good start point to upgrade the graphics card in this machine.

Thanks again!

No problem, recently dragged one out of retirement at work as a 2nd rendering PC, crappy Quadro NVS 295 but 32GB ram. It just sits in the background crunching away.
Was impressed with the design, nice little machines, needs a 2nd socket though 😉

You gotta get a Z600 for the 2nd socket. But yes, HP Z workstations are awesome. Recently got a Z420 and it's a blast of a machine.

Recently I've upgrade this machine with NVIDIA Quadro 5000.
It's more than enough for my purposes. Honestly, it runs fluently any game that I own.

500W is not enough, needs 650W or greater. The Z400 comes with 475W only and uses power hungry components. GTX 280 is earlier than GTX 285 and still about 300W card. Try another PSU with 650W or 750W. my favorite is Seasonic modular models.

Also get this adapter cable to use ATX PSU in Z400:

https://www.moddiy.com/products/ATX-to-HP-Z40 … pter-Cable.html

I have Z220, Z230 and Z420 V2 all works with any GPU cards that I have other than Quadros if can be hooked up and within power limits. I used GTX 960 in two of them. Previously, I had GTX 750ti and GTX 1050ti, and had used HD7750, HD7770, as well, etc ones I forgot about.

If you are handy with modifications:

https://forum.level1techs.com/t/modding-a-des … ples-help/98703

Cheers, pentiumspeed

Thank you very much pentiumspedd for your help.

This topic becomes more interesting post by post.