What controls the clocks?

[SFW]

I have tried 3 sets of clocks on my car and all clocks show the same problem!

the odometer has vanished
the rev counter and speedo bounce around then stop then bounce around again.
all other clocks work well.
i am running an Apexi and the commander will display the revs but the speed for only about a minute then reads 0.

so what actually supplies the clocks with the readings? where is the fault?

i have read many threads the mention F100 and F110 CPU\'s is it one of these?