GPUs have instructions to do other operations, memory copy, load custom kernels, but at their heart they are vector (and tensor, many matrix ops) processors. This is identical to what games require, don't just take my word for it :)

The minimal extra hardware functionality is in the output controllers, i.e. the things that control display port, hdmi etc.

Dedicated AI compute processors (e.g. Nvidia Tesla series) are simply GPUs without outputs, and have no built in cooling fans because they sit in server racks that have high powered cooling mechanisms.

There's no extra magical AI specific functionality in them, they just do vector maths really really well because they are designed for it. :)