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Archived from groups: alt.comp.hardware.overclocking (More info?)
The electromagnetic waves in conductor have a limited speed of about
v=2*10^8 m/s.
The area of the common chip is about 1 cm^2, so we can assume that
electromagnetic wave has to pass about
s=10^-2 m
inside chip.
I will not take relativistic mechanic, because electromagnetic waves
have fixed speed. From
t=s/v
we have time required that signal comes from one side of the chip to
the another side is
t=0,5*10^-10 s
Taking f=1/t
we get that at 20 GHz signal can not even travel from one side of the
chip to another one before arrival of the new clock signal.
If we take average size of one motherboard, here we have a road of
about 10 cm. This means that motherboard clock can not go beyond 2
GHz.
Intel promissed 30 GHz CPU in 2017, with smaller transistors, but
bigger number of them (as usual). Therefore it is not to be expected
that overal size of the CPU chip will be much reduced.
I could conclude that future CPU will work with several clocks. For
example at 30 GHz will work only ALU and some registers, where L1 RAM
cache will drop to 5 GHz and RAM to less than 2 GHz. This means a lot
of wait states, and a very weak effect of the clock raising.
The electromagnetic waves in conductor have a limited speed of about
v=2*10^8 m/s.
The area of the common chip is about 1 cm^2, so we can assume that
electromagnetic wave has to pass about
s=10^-2 m
inside chip.
I will not take relativistic mechanic, because electromagnetic waves
have fixed speed. From
t=s/v
we have time required that signal comes from one side of the chip to
the another side is
t=0,5*10^-10 s
Taking f=1/t
we get that at 20 GHz signal can not even travel from one side of the
chip to another one before arrival of the new clock signal.
If we take average size of one motherboard, here we have a road of
about 10 cm. This means that motherboard clock can not go beyond 2
GHz.
Intel promissed 30 GHz CPU in 2017, with smaller transistors, but
bigger number of them (as usual). Therefore it is not to be expected
that overal size of the CPU chip will be much reduced.
I could conclude that future CPU will work with several clocks. For
example at 30 GHz will work only ALU and some registers, where L1 RAM
cache will drop to 5 GHz and RAM to less than 2 GHz. This means a lot
of wait states, and a very weak effect of the clock raising.
