Additional? - A lot! Even if consider shaders, just new way to run C programs, they have totally different ground - another RAM organization, another variable

Additional? - A lot! Even if consider shaders, just new way to run C programs, they have totally different ground - another RAM organization, another variable types than CPU (or even GPU), another variables visibility (and special methods to deal with it), some very special limitations (on code size, on exec time), and non-guaranteed RAM integrity (yes, for VRAM is normal to lost data). What I see, IF you could fit there, you will got at least one additional high-end CPU core speed for free, even on integrated graphics (for example, nearly all game examples successfully run on intel 630 GPU, and as I understand, CPU there used only to transfer data in-out and to JIT compile).