Stupid question time: if CPUs and GPUs are both kinda needed for a computer, can you substitute a CPU for a GPU? (gpu in a cpu slot)

Around a decade ago Intel had a cancelled project called Larrabee which was going to use older x86 (I think Pentium Pro) cores on a graphics card as they found their older designs worked very well for the workloads graphics cards were running at the time. The project was ultimately shelved before release.
While GPUs and CPUs are both processors they run different instructions and have different workloads. It is theoretically possible to have a GPU run some sort of x86 emulation to run Windows but the performance would likely be awful so as far as I know nobody has attempted this.
You can also run games and other 3d programs through software rendering where the CPU does all of the work the GPU normally does. This is very low performance and rarely usable but still possible.
Tl dr; Yes in theory but not in reality, the software implementations and workloads are way too different and this does not even get into the hardware incompatibilities.

/r/computers Thread