Risc?

When the two competing chip designs came about it was true that a RISC chip could execute instructions faster than a CISC chip of a similar clock speed. Over the years the companies that manufacture CISC chips reduced the instruction set and shortened the number of clock cycles needed to complete an instruction and as such the inherent speed advantage of the RISC chip began to fade in comparison.

While in the past you could say that a 1.0Gz RISC chip was about as fast as a 1.8Gz CISC chip today that comparison would not be quite as factual. The speed of todays 1.8Gz CISC chip is faster, due to other changes made in the chip design and additional features that have been added to the chip than the one made a couple of years ago and it would take a faster RISC chip to keep pace.

That is my understanding of this issue pretty much. I am no expert. There was an article in either Mac Addict or Macworld about this subject a couple of months ago.

All x86 processors are CISC designs but if you look at a low enough level they break instructions down into RISC like micro-operations. CISC designers have learnt a lot over the years and have borrowed some good ideas that have allowed them to close the gap somewhat.

A big part of why the new iMacs appear so much faster than the iMac G5 is that they use dual core processors. For many tasks, especially those that only run on a single processor the speed improvement is only 10% - 25% according to MacWorld's benchmarks http://www.macworld.com/2006/01/features/imaclabtest1/index.php
What gains people will actually see with the new machines depends on the kind of work they are doing.

Remember that benchmarks don't tell the whole story. They really only show performance in a single, specific, situation. Lies, ****** lies and benchmarks, etc.

I am just an interested layman in processor architecture, but are you saying that apples explaination about MHz myth ( see video here http://www.esm.psu.edu/Faculty/Gray/movies.html) doesn't hold water for comparing the present day processors? Sorry for asking in such a way; for the knowledgeable people here my question might sound dumb or vague.