I recently upgraded my proxmox host and went with a Ryzen 5700G for GPU accelerated media enconding. Turns out my media server does recognize the iGPU but doesn't use it not matter the video format.
While CPU encoding works just fine with the performance at hand, I'd still prefer hardware acceleration and I am thinking about getting a PCIe x1 to x16 riser (or just removing the blocking part of an x1 slot...) to install my old Quadro P600 for NVENC, which worked fine in the previous hosts x16 slot when I didn't have a high bandwidth network card.
The board (MSI B450M PRO-VDH PLUS) has 1x PCIe 3.0 x16 used by an Intel X520-DA2 and 2x PCIe 2.0 x1 currently not in use.
My question is if the limited bandwidth of PCIe 2.0 x1 will influence the NVENC capabilities in a significant manner and if you have recommendations for trustworthy adapters which won't start a fire, preferrably available to buy in germany.
It really depends. I've seen PCs that use nonstandard parts just so you must use original parts, and systems which made use of new things like 12 volt only PSU really early and had great designs for easy access in a compact machine.