First of all take into account thtat connecting a PCI-E x16 card in a PCI-E x8 slot will work but you would receive half of the performance as you are not covering all the pins in the connection.
Secondly i was looking at NVIDIA for your model and i could not find it anywhere. You need to make sure that your GPU is supported by the ESXi version you are running, the hardware and that you have the correct drivers associated. Take a look here: https://docs.nvidia.com/grid/10.0/product-support-matrix/index.html
thanks for your reply. I am aware that putting a x16 card in a x8 slot only brings half the speed. It's just that the card was lying around and I hoped that I somehow can use it without any further expenditures. The supported graphics cards are not very cheap...
I am also aware that my graphics card is not officially supported by vmware ESXi, but was just hoping as written before.
Here is a link to my GPU, maybe that is of any help: https://www.nvidia.com/content/dam/en-zz/Solutions/design-visualization/quadro-product-literature/NV-DS-NVS-310-May12-US…
Using a device that is not supported for LAB purposes is perfectly fine but is also best effort to make it work. Did you find a suitable driver for that card? Try multiple combinations of drivers. Hopefully one of them will match and you will be able to use it.
It's been quite a while, but I got a solution. After I upgraded to ESXi 7.0 PCIe passthrough can be activated.