I want to install ESX(i) on it and have client OS's on it that have a dedicated video card each.

You are WAY off base. VM's are not designed for performance.

VM's are not designed for graphics.

You cannot dedicate hardware to a VM (realisitically) anyway, certainly not assign a graphic card to a VM.

Not sure what you are trying to achieve, but "graphics" are an END user experience NOT the server. You can rip the graphic card out, VM will still run, you just can't see anything from the console on that server ..

RDP to the VM, that graphics comes from the workstation where the RDP session is, not the server.