Looks like the A4000 has low memory bandwidth (50% of a 4090?) which is the limiting factor for inference usually. But they are efficient - if you can get them

Looks like the A4000 has low memory bandwidth (50% of a 4090?) which is the limiting factor for inference usually. But they are efficient - if you can get them for cheap, probably a good entry setup? If you like running models that need a lot of VRAM, you‘ll likely run out of PCIe slots before you are done upgrading.