The speed of light is wicked fast. Converting it to feet per second =
983571056 which is almost 1 billion feet/second.
5 GHz = 5 billion times per second.
So, how far will a beam of light travel when a clock at that rate ticks once?
(983571056 feet/second) x (1 second/5000000000 ticks) x (12 inches/1 foot)
2.36 inches per tick!
If you do the same for 4.0 GHz, you get 2.95 inches.