AMD Trumps Intel

[BEST45CAL]

Semiconductors:


AMD Trumps Intel
Arik Hesseldahl (javascript:newWindow('Hesseldahl')), 10.19.04, 5:25 PM ET

NEW YORK - Chipmaker Advanced Micro Devices made its latest claim to the title of fastest PC microprocessor today, when it announced a pair of new chips aimed at the high end of the PC market.



http://www.forbes.com/technology/2004/10/19/cx_ah_1019chips.html

[DoctorDoom]

The speed race is utterly meaningless, inasmuch as the CPU is the only thing on the MOBO that can run that fast. Off the chip, there are immutable and inescapable physical limitations as to the speed that's possible. Ergo all that will be achieved is the CPU running more do-nothing commands while waiting for the system to catch up to it.

If the companies could design a chip with a gig of cache RAM, it might be worth the extra speed. The system could load and run entire programs on the chip itself, interfacing with the outside world only to fetch or store data, or to talk to some peripheral. That would result in spectacular speed increases. What it would prove is anyone's guess, but it would be quick.

The speed bottlenecks in the average modern computer have nothing to do with CPU clock speed. The limitations are created by having to communicate constantly with comparatively slow RAM, the PCI/AGP bus, and especially the hard drive. Slow increases in speed are being made re the FSB and the RAM, but there will come a point when the lengths of the PCB runs will become a limiting factor.

The clock period at 1 GHz is 1 nanosecond. In that time, light travels about 11.8 inches. Ergo that's the maximum speed at which electricity can flow in a conductor. If the clock frequency goes high enough, propogation delay in the conductors can lead to sync problems. The CPU issues a command, and when the response gets back to it, there's a timing error because it's already performing the next instruction.

If the CPU has to pace itself to keep the system properly synced, then the value of multi-GHz CPUs is limited. It's a bit like driving a Lamborghini in city traffic. Who cares if it can go 200 MPH if traffic is crawling along at 20-30?

Fundamental changes in the machines' physical design will be required before these super-CPUs will be anything more than gee-whiz bragging points.