I have a similar situation. I want to install an NVIDIA Quadro RTX6000, but my Precision 3930 currently only has one 550W PSU.

Any luck on setting up the non-redundant power supply?

No luck at all. I've been trying everything I can find. I've even tried to set up an external PSU for the graphics card (didn't work). I've used pro-support many times to see if there is anything that can be done. They are going to see about replacing my motherboard with one that is set up for non-redundant power. We'll see if that amounts to anything. If you configure the new 3930 racks on dell.com you can select non-redundant power. So maybe with that motherboard it will work and I'll finally have 1100w.

Update: Yesterday I was able to get my external PSU to fire up the GPU while my 2 x internal PSU's run the rest of the system. It's a little less than ideal, but it is working so far.

From my experience, I think by adding a second internal PSU and purchasing the Dell GPU power cable, your system should be able to use the NVIDIA Quadro RTX6000. Hope this helps!

Hi Sullen

Glad to hear you were able to get it working! I ended up buying a new server with the redundant power supply, but I still can't get the GPU to work. I'm using a regular PCIe GPU power cable, and from your results, it seems like I need the DELL GPU power cable. Unfortunately, I can't find one for the Precision. (I found one for a PowerEdge, but the connector is a different size.) Do you remember the part number, or do you have any information about the pin assignments and so forth?

I hope the photos are clear enough to see the connections. 

I got this cable for my 3930 rack:

GPU Power Cable (short 8x6)

Manufacturer Part MGKMR 

Dell Part 470-ADFR 

Order Code 470-Adfr 

I found it under accessories for the 3930 rack in the business side of the house.

https://www.dell.com/en-us/shop/gpu-power-cable-short-8x6/apd/470-adfr/power-cooling-data-center-infrastructure

Thank you very much for the information and for the quick response!

I can't see the second picture, but from the first I can tell that the pin assignments are very different than the standard PCIe cable. Are the pins which are hidden in this image all grounds?

Pin assignments (that I think I can see).

?                ?               ?        Yellow

Yellow(x2)  GND(x2)  GND  GND

I looked for the cable on the DELL website, but it doesn't seem to be available here (I'm in Japan). I'll try asking them directly. If I can't get it from DELL, I think the only option will be to make the cable myself.

Thanks again. You've already been a big help.

 Here is the free end that I don't use. 

Happy to help! I'll attach better photos.

I think these two will be the most helpful.