I use a MacPro 5.1 Monterey with a RX 580, mostly for FCPX and photos, no gaming.
I'm not interested in benchmarks, only in real-life use for FCPX and photos.
Is there a point updating the card or will I get similar render times and noice reduction times with Neat Video?
I also searched Youtube and found no comparison of this sort.
Thanks!
This is a vey much complex topic that have no simple answers since the performance gains depend very much on the type of video that you are working/exporting.
First thing, there is no RX 6900XT that fits inside the MacPro5,1 as it came from the factory, even for the smallest one you will need to relocate the PCIe fan assembly and make a Pixla's mod to power it.
There are probably two RX 6800 that fit inside the MacPro5,1 without relocating the PCIe fan assembly, both Dell/Alienware models that are difficult to find, but you still need to do the Pixla's mod. There are posts about these here, even with the Alienware PCs that came with the GPUs, sometimes cheaper to get the whole used PC with the GPU than the GPU itself.
Second thing, talking specifically FCPX here, the advantages of NAVI GPUs are basically the very much improved ASICs for offloading the compression/decompression/color grading from the CPU.
AMD developed a lot the ASICs over the years and each new generation of GPUs have greater improvements. From memory, the VEGA 20 (for example the much loved AMD VII) have two UVD 7.2 units capable of 8K while a Polaris (RX 480/580) have just one and version 6.0, limited to 5K.
AMD further improved NAVI 2x generation capabilities with Video Core Next 3.0 adding 8K 10b, so, there are substantial gains upgrading the GPU if you need a lot of compression/decompression, color grading or exporting to 10-bit H.265.
Since RX 6600 to RX 6900XT all have the exact same VCN ASIC, no need to get the most powerful GPU from the RX 6xxx line to get the all improvements, a plain RX 6600XT will get you there without Pixla's mod or relocation of the PCIe fan assembly.
Anyway, the performance gains could be huge, but that depends very much on the type of video you are working, what you are doing with it and how you are exporting it from FCPX, no video review/benchmark will ever cover all possibilities here.
