OT: Impedance

  • Thread starter Thread starter Jacky Luk
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Jacky Luk

When the operating frequency of the processor gets very high, there should
be insufficient current or voltages (forget which) to drive the device. Is
that why higher voltages are applied when the CPU gets overclocked or in a
high frequency range? like Pentium 4 2.6GHz

Thanks
Jack
 
Jacky said:
When the operating frequency of the processor gets very high, there should
be insufficient current or voltages (forget which) to drive the device. Is
that why higher voltages are applied when the CPU gets overclocked or in a
high frequency range? like Pentium 4 2.6GHz

Thanks
Jack
Click to expand...
It is not as simple as higher frequencies requiring higher voltages. It
is also dependent on the size of the components. The larger the
components the more current required to change them. If you are going
to make the same component switch faster you will need a higher voltage
to get enough current flow fast enough. Modern CPUs use much smaller
component sizes than the older CPUs and can use a lower voltage. The
lower voltage (and current) is important because the higher they are the
more heat they generate.
 
The problem is not just heat, too much voltage will short
the CPU internally because the circuit paths are so close
together.

In a DC circuit resistance is the measure of the wire to
carry current. Impedance is the AC current resistance
equivalent and the value is dependent of frequency. They
use choke coils to control current, the value of a choke
varies with the frequency.


message
| Jacky Luk wrote:
| > When the operating frequency of the processor gets very
high, there should
| > be insufficient current or voltages (forget which) to
drive the device. Is
| > that why higher voltages are applied when the CPU gets
overclocked or in a
| > high frequency range? like Pentium 4 2.6GHz
| >
| > Thanks
| > Jack
| >
| >
| It is not as simple as higher frequencies requiring higher
voltages. It
| is also dependent on the size of the components. The
larger the
| components the more current required to change them. If
you are going
| to make the same component switch faster you will need a
higher voltage
| to get enough current flow fast enough. Modern CPUs use
much smaller
| component sizes than the older CPUs and can use a lower
voltage. The
| lower voltage (and current) is important because the
higher they are the
| more heat they generate.
 
Talking about size, I feel really uneasy for the PCI Express, it is scary
because it's like throwing you back to the age of Microchannel, ISA and VESA
Local Bus, it is so long and freaky. And the socket (AMD64) for the CPU is
so "Pinny", Is it going to be a new trend of making PCs big again? and when
the new generations of CPU come up, I would guess the limitation of number
of pins would be 512 or alike... How can you put so many pins on one socket
512 bits for data, not much left for Control and Address buses!
Thanks
Jack
 
Jacky said:
Talking about size, I feel really uneasy for the PCI Express, it is scary
because it's like throwing you back to the age of Microchannel, ISA and VESA
Local Bus, it is so long and freaky. And the socket (AMD64) for the CPU is
so "Pinny", Is it going to be a new trend of making PCs big again? and when
the new generations of CPU come up, I would guess the limitation of number
of pins would be 512 or alike... How can you put so many pins on one socket
512 bits for data, not much left for Control and Address buses!
Thanks
Jack
Click to expand...

I don't think they are going to be able to add too many more pins or
data lines as the length data has to travel will reach a point that the
speed of light in copper will be a major concern, along with RF
interference.
 
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