Hi Leo, I was exactly in your situation few weeks ago.
First of all "All Quadro RTX 4000 are same even though they are labeled as Dell/HP/PNY etc. I ended up buying 2 HP Quadro RTX 5000 and I am not sure if I am entirely happy with that decision.
These HP/Dell Quadros are modified to work specifically in HP and Dell computers, such as HPz 4 and such. They come with additional design to fit in the space available in HP or Dell machines. Also they are little bit cheaper.
One major difference is that the Packaging comes with a decal that saying that the warranty will be void if used in machines other than HP. It comes with 3 years warranty and to get any technical or warranty support you need to provide them the serial of the HP machine that you are using this card in. In most part these quadros will work great, however if are not using these cards in HP or Dell machine then you will not have any warranty. It is a scary feeling that I have invested this much money to buy a Quadro cards and It is not covered by a warranty.
I recommend buying Quadros directly from Nvidia or check what kind of warranty coverage does PNY has.
What kind of jobs you do with Quadro?