How fast does a CPU transfer data?

How fast does a CPU transfer data?
As with any device that utilizes electrical signals, the data travels very near the speed of light, which is 299,792,458 m/s. How close to the speed of light a signal can get depends on the medium (type of metal in the wire) through which the signal is traveling. Most electrical signals are traveling at about 75 to 90% the speed of light.
Could a GPU be used in place of a CPU?
No. Although GPU's are capable of processing data and doing many of the same things as a CPU, it lacks the ability to perform many of the functions required by typical operating systems and software.