Definitions are a little fuzzy but "compute" is often used to distinguish between "compute," as in CPU, memory, and disk. And GPU is a very specialized kind of compute power. There's really no "grammatically correct" here these are different senses of the word. "Computing power" doesn't exactly have the same sense of specifically referring to a CPU or GPU as "compute power."
Since we adopted English as the standard language, complete with its penchant for butchering words by shortening them for the sake of convenience and speed.
I wonder what people said about "bus" back in the day, especially those who knew Latin.