“This article is concerned with the technical differences between [x86 and PowerPC] not the market differences,” writes Nicholas Blachford for OS News.
“The x86 family of CPUs began life in 1978 as the 8086, an extension to the 8 bit 8080 CPU. It was a 16bit CISC (Complex instruction Set Computing) processor. In the following year the 8088 was introduced which was used in the original IBM PC. It is this computer which lead to todays PCs which are still compatible with the 8086 instruction set from 1978,” Blachford begins. “The PowerPC family began life with the PowerPC 601 in 1993, the result of a collaboration started in 1991 between Apple, IBM and Motorola. The family was designed to be a low cost RISC (Reduced Instruction Set Computing) CPU, it was based on the existing IBM POWER CPU used in the RS/6000 workstations so it would have an existing software base.”
“x86 has the advantage of a massive market place and the domination of Microsoft. There is plenty of low cost hardware and tons of software to run on it, the same cannot be said for any other CPU architecture. RISC may be technically better but it is held in a niche by market forces which prefer the lower cost and plentiful software for x86. Market forces do not work on technical grounds and rarely chose the best solution. Could that be about to change? There are changes afoot and these could have an unpredictable effect on the market,” Blachford explains.
“Computers are now so fast it’s getting difficult to tell the difference between CPUs even if their clock speeds are a GHz apart. What’s the point of upgrading your computer if you’re not going to notice any difference? How many people really need a computer that’s even over 1GHz? If your computer feels slow at that speed it’s because the OS has not been optimised for responsiveness, it’s not the fault of the CPU – just ask anyone using BeOS or MorphOS. There have of course always been people who can use as much power as they can get their hands on but their numbers are small and getting smaller. Notably Apple’s software division has invested in exactly these sorts of applications,” writes Blachford.
Blachford concludes, “What is going to be a hurdle for x86 systems is heat. x86 CPUs already get hot and require considerable cooling but this is getting worse and eventually it will hit a wall. A report by the publishers of Microprocessor Report indicated that Intel is expected to start hitting the heat wall in 2004. x86 CPUs generate a great deal of heat because they are pushed to give maximum performance but because of their inefficient instruction set this takes a lot of energy. In order to compete with one another AMD and Intel will need to keep upping their clock rates and running their chips at the limit, their chips are going to get hotter and hotter.”
“You may not think heat is important but once you put a number of computers together heat becomes a real problem as does the cost of electricity. The x86’s cost advantage becomes irrelevant when the cooling system costs many times the cost of the computers,” writes Blachford. “RISC CPUs like the 970 are at a distinct advantage here as they give competitive performance at significantly lower power consumption, they don’t need to be pushed to their limit to perform. Once they get a die shrink into the next process generation power consumption for the existing performance will go down. This strategy looks set to continue in the next generation POWER5.”
“The POWER5 (of which there will be a “consumer version” [read: G6]) will include Simultaneous Multi-Threading which effectively doubles the performance of the processor unlike Intel’s Hyper Threading which only boosted the performance by 20% (although this looks set to improve). IBM are also adding hardware acceleration of common functions such as communications and virtual memory acceleration onto the CPU. Despite these the number of transistors is not expected to grow by any significant measure so both manufacturing cost and heat dissipation will go down,” writes Blachford.
There is significant depth and much more to read in the full article here.