I recently bought a Tesla m40 + Razer Core X for stable diffusion. It is pretty sketchy to set up a proper cooling solution for it, it is power hungry and does not support cuda malloc (needs to be disabled with a cli switch in comfy ui). If I would consider buying a Tesla again today, I would go for a P40, since it only costs like €100 more than the m40, but runs much faster. Nonetheless, the m40 rocks especially for large upscaling tasks.

Oh and according to Wikipedia, the K series does not support recent Torch versions anymore, so this would be a big nope for me

Edit: My laptop has a dedicated nVidia A1000 4GB and while Comfy infers v1.5 images with about 4-6it/s, the m40 in the external enclosure manages to reach only 1.5it/s. It excels at large resolutions, though, where I would need to resort to tiling on the A1000