Increasing CPU speed will maintain the current level of CPU utilization, in the case where the process mix is compute bound, or decrease CPU utilization, in the case where the process mix is I/O bound.

I/O-bound programs have the property of performing only a small amount of computation before performing IO. Such programs typically do not use up their entire CPU quantum. CPU-bound programs, on the other hand, use their entire quantum without performing any blocking IO operations. Consequently, one could make better use of the computer's resources by giving higher priority to I/O-bound programs and allow them to execute ahead of the CPU-bound programs.

A program is CPU bound if it would go faster if the CPU were faster, i.e. it spends the majority of its time simply using the CPU (doing calculations). A program that computes new digits of π will typically be CPU-bound, it's just crunching numbers.

A program is I/O bound if it would go faster if the I/O subsystem was faster. Which exact I/O system is meant can vary; I typically associate it with disk. A program that looks through a huge file for some data will often be I/O bound, since the bottleneck is then the reading of the data from disk.

Any CPU will have an I/O which en ply external devices data transfers. The CPU internally will process data. While both are data bus they are definitely not the same