Which graphics card is suitable for my workstation?

Hi there,
I'm new to this forum...

I have the following question: Which graphics card is suitable for my workstation?
Unfortunately, my workstation is not powerful enough for 4K video editing & color editing, it doesn't have enough VRAM, so I now want to install a better graphics card! What can you recommend me?

My projects with my BMPCC6K Pro are in 6k and 4k BRAW (in the timeline at DaVinci-Resolve 4K/UHD) and I choose P3 as the output format in order to then burn the films onto a Blu-Ray.

My "Fujitsu Workstation CELSIUS M7010X" has the following specifications:
Intel Core i9-10920X , 12C CPU @ 3.50GHz 3.50GHz
64.0 GB RAM (63.6 GB usable)
Windows 10 Pro (Version 22H2) / 64bit

My desired graphics cards would be:
NVIDIA 3080ti 16GB, NVIDIA 3090 24GB, NVIDIA 4080 16GB, NVIDIA 4090 24GB

Sub-questions:
If they can be found anywhere on the market, where is the best place to buy them!
What is the current situation, a year or two ago the market was very thin to find a suitable card?
Does anyone of you know?

The question is, can any of these cards be built into the workstation at all?
Can anyone tell me anything about this?
Of course I would need a larger power supply, maybe 1000V!

According to the data sheet of this workstation, the following graphics cards can be safely installed:

Ultra-high-end 3D: NVIDIA® Quadro® RTX 6000, 24 GB, PCIe x16, 4 x DisplayPort, 1 x Virtual Link
Ultra-high-end 3D: NVIDIA® Quadro® P6000, 24 GB, PCIe x16, 1 x Dual Link DVI-D, 4 x DisplayPort
Ultra high-end 3D: NVIDIA RTX™ A5000, 24 GB, PCIe x16, 4 x DisplayPort
Ultra high-end 3D: NVIDIA RTX A6000, 48 GB, PCIe x16, 4 x DisplayPort
High-end 3D: NVIDIA® Quadro® RTX 4000, 8 GB, PCIe x16, 3 x DisplayPort, 1 x Virtual Link
High-end 3D: NVIDIA RTX™ A4000, 16 GB, PCIe x16, 4 x DisplayPort
High-end 3D: NVIDIA RTX A4500, 20 GB, PCIe x16, 4 x DisplayPort

What would be an option if my wish didn't work?

Can you help me?


Best... T.

Just get the biggest one you can afford.