posted by Nicholas Blachford on Wed 9th Jul 2003 16:43 UTC

"Conclusion, References"

x86 is not what it's sold as. x86 benchmarks very well but benchmarks can and are twisted to the advantage of the manufacturer. RISC still has an advantage as the RISC cores present in x86 CPUs are only a marketing myth. An instruction converter cannot remove the inherent complexity present in the x86 instruction set and consequently x86 is large and inefficient and is going to remain so. x86 is still outgunned at the high end and perhaps surprisingly also at the low end - you can't make an x86 fast and run cool. There is a lot of marketing goes into x86 and the market -technical people included- just lap it up.

x86 has the desktop market and there are many large companies who depend on it. Indeed it has been speculated that inefficient or not, the market momentum of x86 is such that even Intel, it's creator may not be able to drag us away from it [14]. The volume of x86 production makes them very low cost and the amount of software available goes without saying. Microsoft and Intel's domination of the PC world has meant no RISC CPU has ever had success in this market aside from the PowerPCs in Apple systems and their market share is hardly huge.

In the high end markets, RISC CPUs from HP, SGI, IBM and Sun still dominate. x86 has never been able to reach these performance levels even though they are sometimes a process generation or two ahead. RISC vendors will always be able to make a faster, smaller CPUs. Intel however can make many more CPUs for less.

x86 CPUs have been getting faster and faster for the last few years, threatening even the server vendors. HP and SGI may have given up but IBM has POWER5 and POWER6 on the way and Sun is set to launch CPUs which handle up to 32 threads. Looks like the server vendors are fighting back.

Things are changing, Linux and other Operating Systems are becoming increasingly popular and these are not locked into x86 or any other platform. x86 is running into problems and PowerPC looks like it is going to increasingly become a real, valid alternative to x86 CPUs both matching and exceeding the performance without the increasingly important power consumption or heat issues.

Both Amdahl's Law (of diminishing returns) and Moore's Law date from around the same time but notably we hear a great deal more about Moore's law. Moore's Law describes how things are getting better, Amdahl's Law says why it's not. There is a difference however: Moore's Law was an observation, Amdahl's Law is a Law.


[1] John Cocke, inventor of RISC (obituary),3858,4469781,00.html

[2] SPEC benchmark results

[3] Amdahl's Law Simplified - Richard Wiggins

[4] Speed differences in different languages

[5] Coding competition shows humans are better than compilers

[6] Combined CPU Benchmarks

[7] C3 V's Celeron benchmarks

[8] Speculation on the PowerPC G5

[9] Details of the 64bit bridge can be found in the Software Reference Manual.

[10] Apples G5 benchmarks

[11] ICCs optimisations can greatly effect performance

[12] But [11] does not appear to continue into real life code

[13]* Article on G5 benchmarks,,t271-s2136537,00.html
*I do not know if this is an exact quote.

[14] Escape from planet x86 - Paul DeMone

Further Reading
Article covering the differences between RISC and CISC

Article on PowerPC 970

About the Author:
Nicholas Blachford has been interested in CPUs for many years and has written on the subject for OSNews before. He works for Genesi who produce the Pegasos G3 / G4 PowerPC based motherboard and the MorphOS Operating System.

Table of contents
  1. "History, Architectural differences, RISC Vs CISC, Current state of these CPUs"
  2. "Law of Diminishing , Performance, Vector Processing and Power Consumption differences"
  3. "Low Power x86s, Why The Difference?, To RISC Or Not To RISC, PPC and x86 get more Bits"
  4. "Benchmarks, the Future"
  5. "Conclusion, References"
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