[gergytree]

> You seem to be mixing up different concepts.

This is oversimplifying but my understand is that graphics programs like games send data and instructions as a job into a queue managed by operating system to the CPU which then has to then quickly decide what to do with it. GPU's function as a sort of co-processor in that the CPU will offload a portion or all of the instructions/data of jobs where GPU processing is indicated in the job instructions. This is why all GPU processing involves CPU overhead. Also GPU's are somewhat bottle-necked by this whole process.

It's my impression that current trends like Mantle, DX12 and Vulkan are trying to reduce the amount of stuff the CPU has to do to process jobs intended for the GPU. But they can never really eliminate the role of the CPU even in something like an ARM chip is embedded on the GPU board that handles most of the processing that the CPU would have done.

tl;dr - CPU is what makes the computer happen but the GPU is like a dedicated graphics co-processor.

Feel free to correct me if I'm wrong.