Clocks and Timers can be a number of things in computers.
Clocks can be.... Clock Speed such as 700Mhz GPU and 4.2Ghz CPU, FSB 220Mhz of an overclocked system with 10% memory overclock, The clock you see in the corner system tray, internal system clock with date/time, and more
Timers can be... scheduled tasks, scheduled updates, system behavioral parameters to abide by within a specific window of user usage such as a system that when idle crunches scientific data, but doesnt do this during a 8 hour window of user usage. Timing is also critical in video game design and software that requires delay timers to control the rate of execution in a powerful CPU and GPU system so that the games run at a constant speed which works hand in hand with a Real Time Clock function so that say a game that is running on a 800Mhz Pentium III will run at the same speed as a 4.2Ghz system vs 5 times faster game execution to where you are playing a game that runs fine on a 800Mhz system but it runs 5 time faster on a 4.2Ghz system and the game is then unplayable. (* Early games in the 8088 CPU era had issues like this running on the newer 286 and some 386 systems, and some had a Turbo button that could be used to change the FSB of the system so that for example a 12Mhz 286 could run at 16Mhz with the Turbo button enabled, but when running older games that run too fast, you can shut the Turbo button off and have it run at 12Mhz which is closer to the 4.77Mhz CPU that the game was designed to execute around.)
