installing 3x RTX 4000 on Z840: Power Cable arrangement

[skt001]

Hi, I would like to upgrade the workstation with 3 x RTX 4000 graphic cards.

I have one RTX 4000 attached to two 6 pin cables coming from power supply with a cable like this:

The two additional cards came with two more of these, but there are no more 6 pins left to attach to.

How should I proceed?

A diagram/image with some explanation would be appreciated.

Thanks.

[DGroves]

the stock 850 watt supply is not going to support 3 RTX 4000 video cards as each card will draw around 160 watts

you should be able to do two 4000 cards on the stock supply as this is a HP supported config on the stock supply

the optional 11150/1200 watt supply can do 3 video cards (but it's not a HP supported configuration) the upgraded supply will have three  6 pin GPU pwr connectors instead of the stock 850 watt supply's two and you will need  HIGH QUALITY 6 to 8 pin adapters

https://www.bhphotovideo.com/c/product/1207528-REG/hp_n1g35aa_6_pin_to_8_pin_power.html

the HP adapters are not cheap, but they also don't start fires like many cheap no name adapters , think about the total cost of the z840 and video cards............want to risk them to save 150.00?

[skt001 · Accepted solution]

Thank you for the reply.

My power supply is 1125W but it has only two 6 pin connectors G1 and G2.

https://youtu.be/HKSc5l0cvsw

I found this video, it showed how to change power connector to a 3x 6 pin connector G1, G2 and G3.

As per your suggestion if I put HP 6 to 8 pin connector on each of three connectors, each will power one RTX 4000.

(Many thanks for quick reply)

Also, connecting more than one GPU will need two fans in GPU section. If not, it will show cooling fan error.

A good thing, as there will be too much heat needing dispersion.

Please let me know if I understood it correctly.

[DGroves]

you got it,..................i'm curious why the two rtx 400 cards? since SLI is no more, you must be using them a coprocessors right?

[skt001]

I do 2D/3D concept art and 3D environment design.

This workstation sees fluid renderings, Foliage and particle effects on regular basis.

Blender, C4D and Houdini - all three let me use multiple GPUs for rendering.

Eventhough I am stuck with 8 GB of Physical Graphic memory, I have 128 GB VRAM (256 GB Total) to handle larger projects, which are not that frequent.

3x RTX 4000 Cut down rendering time by a lot.

RTX 5000 and beyond are still very costly(1.9x more per card and beyond)  for our small scale set up.  

[DGroves]

have you looked into rendering farm software which allows multiple systems to render a image not all software or projects benefit but if yours do then it's a worthwhile way to render on cheaper gpu(s)

https://vfxfarm.com/soft/houdini.php

https://us.rebusfarm.net/en/lets-go/download

https://www.squidnetsoftware.com/

https://knowledge.autodesk.com/support/3ds-max/troubleshooting/caas/sfdcarticles/sfdcarticles/Networ...

[skt001]

Great Suggestion.

Will look into it.

Thanks.

[DGroves]

the z840 when bought "NEW" from HP with the upgraded supply will always come with the wiring harness that has 3 GPU power connectors

the z840 with the stock 850 watt supply will only have the harness with the 2 GPU power connectors

it appears that someone bought/acquired a z840 that came with the 850 watt supply and replaced it with the higher wattage one not realizing that you need to add the missing GPU power cable to the existing wiring

i've posted on this before and listed the HP part number of the necessary cable, search this forum for the post if interested