That's 8 (not 4), on a NVIDIA platform board to start with.

You can't buy them as "GPU"s and integrate them to your system. NVIDIA sells your the platform (GPUs + platform board which includes switches and all the support infra), and you integrate that behemoth of a board to your server, as a single unit.

So that open server and the wrapped ones at the back are more telling than it looks.

You missed the black unwrapped boxes in the background....