Low End Mac's Online Tech Journal

AltiVec vs. Pentium III

A Little Bad Math Goes a Long Way

Dan Knight - 2000.11.21

If there's one thing that gets my goat, it's bad math and statistics.

In Gauging the Gigaflops Gap, Don Granberry of ZDNet tries to explain how the G4 with AltiVec is superior to the Pentium III. It's actually a fairly accessible explanation, but the numbers are flawed.

Granberry uses the following table to compare a 700 MHz PIII with a 500 MHz G4:

It's a nice table. It's clearly labeled. The facts are clearly established. But there's one piece of misleading data: CPU speed doesn't mean a thing when you're looking at how many clock cycles are used.

MHz for MHz, the G4 is 3.68 times more efficient at these particular functions (or, as Granberry puts it, the G4 does the same work in 27% as many processor cycles).

This wouldn't be a problem, except that later in the article he links clock speed to this. Which wouldn't be a problem, except that he doesn't apply the same clock speed to both processors.

Multiplying 3.68 by 700 MHz, Granberry states that a 2.6 GHz Pentium III would match the performance of a G4/500 on these tests - but it just isn't so.

The problem is the misleading data (remember how story problems would sometimes introduce numbers that were not necessary to solve the problem?) brought him to the wrong number. No matter how precise the math, if you're multiplying the wrong number, you get the wrong result.

Instead of 2,576 MHz, he should have multiplied 3.68 by 500 MHz, resulting in a Pentium III running at 1,840 MHz to match the G4/500's performance on these particular functions.

Of course, Apple is now shipping the Power Mac G4/500 in a dual-processor configuration, so it would take 3,680 Pentium III MHz to match it. For the sake of convenience, let's say a quad-processor PIII/900 system would match the dual-processor G4/500 on these vector functions.

Whether this means much in the real world is another question entirely, but at least we have the math right.

Recent Online Tech Journal Columns

• Optimized Software Builds Bring Out the Best in Your Mac, 06.30. Applications compiled for your Mac's CPU can load more quickly and run faster than ones compiled for universal use.
• Low End Mac's Safe Sleep FAQ, 06.15. What is Safe Sleep mode? Which Macs support it? How can you enable or disable it? And more.
• The Original Macintosh, 01.12. An in-depth look at the original Macintosh and how it shaped future Macs.
• The Innovative Lisa, 01.08. Apple's Lisa and how it paved the way for the Macintosh.
• More in the Online Tech Journal index.

Links for the Day

• Mac of the Day: Lisa, Jan. 1983 - The ancestor of the Macintosh had a mouse, a graphical interface, and a $10,000 price tag.
• Group of the Day: Unsupported OS X is for those using OS X on unsupported hardware.
  
• March 22 in LEM history: 00: Macs and digital video - 01: My Performa - Fun at CompUSA75 Mac Advantages - 02: Don't try this at home - History of portable computing - 04: Prolong battery life - 05: Symantec's ravings spread FUD about OS X security - 06: Picking a Power Mac G4 - France and the end of DRM
• Support Low End Mac

Recent Content on Low End Mac

• Does iPhone OS Need Multitasking?, iCab Comes to iPhone, Canada's Proposed iPod Levy, and More, iNews Review, 03.19. Also the iPad paradox, Freescale demos $200 tablet, gardening apps, aluminum iPhone stand, steel iPhone case, and more.
• Could iPad Replace the Mac?, Mac Sales Up in 2010, Avoiding Windows 7 'Whenever Possible', and More, Mac News Review, 03.19. Also why your next Mac may be an iPad, science blogger abandons Apple, the benefits of standing while working, and more.
• The Mobile System Stampede, Lithium Battery That Can't Explode, Affordable SSD Options, and More, The 'Book Review, 03.19. Also June 2007 MacBook Pro external display issue, laptop stands, 1 TB ultraportable hard drive, Mini DisplayPort/HDMI adapter, and more.
• How to Zoom Your Browser for a More Readable Web, Steve Watkins, The Practical Mac, 03.18. Instructions for zooming text and pages in Safari, Firefox, Camino, and Opera.
• CardBus WiFi, the Shiira Browser, Ridding the Web of Flash, and Macs vs. PCs, Charles W. Moore, Miscellaneous Ramblings, 03.18. Mac longevity, Shiira speed, ambidextrous Mac and Windows use, and how Flash benefits Apple.
• How Ad Blocking Hurts Your Favorite Websites, Charles W. Moore, Miscellaneous Ramblings, 03.18. Ad income keeps the Web free. Blocking online ads hurts your favorite websites.
• Taking Apart the 12" PowerBook, John Hatchett, Recycled Computing, 03.17. There are a lot of steps involved in disassembling a 12" PowerBook. Proceed with caution.
• More links in our archive.

Recent Deals

• Best 13" MacBook & MacBook Pro Deals, 03.22. Used 1.83 GHz, $570; 2.0, $599; 2.4 GHz, $889; refurb 2.26, $849; new, $900 after rebate; Pro, $1,119 a/r, 2.53, $1,399 a/r.
• Best Power Mac G5 Deals, 03.22. 1.8 GHz single, $399; dual, $445; 2.0, $609; 2.5, $724; 2.7, $799; 2.3 GHz dual-core, $669; 2.5 GHz Quad, $799.
• Best AirPort Deals, 03.22. Refurb AirPort Express, $79; new, $95; refurb dual-band AirPort Extreme Hub, $129; new simultaneous dual-band, $168.
• Best Intel iMac Deals, 03.17. Used 17" from $600; 20" from $750; 24" from $825; refurb 21.5" nVidia, $999; new, $1,099; refurb Radeon, $1,299; new, $1,399; refurb 27" 3.06, $1,499; more.
• Best G5 iMac Deals, 03.17. 17" 2.0 GHz, $380; 1.9 GHz iSight, $479 shipped; 20" 1.8 GHz, $509 shipped; 2.1 GHz iSight, $549 shipped.
• Best Time Capsule Deals, 03.17. Close-out 500 GB, $140; new 1 TB, $279; used 2 TB simultaneous dual-band, $400; new, $455. Shipping included.
• Best iPad Deals, 03.16. 16 GB iPad, $499; 32 GB, $599; 64 GB, $699; 16 GB with 3G, $629; 32 GB 3G, $729; 64 GB 3G, $829. Free ground shipping.
• More deals in our archive.

About LEM | Support | Usage | Privacy | Contacts

Entire Low End Mac website copyright ©1997-2010 by Cobweb Publishing, Inc., unless otherwise noted. All rights reserved. Advice presented in good faith, but what works for one may not work for all. Please report errors to .
  LINKS: We allow and encourage links to any public page as long as the linked page does not appear within a frame that prevents bookmarking it.
  Access our RSS news feed at http://lowendmac.com/feed.xml.
  Email may be published at our discretion; email addresses will not be published without permission, and we will encrypt them in hopes of avoiding spammers. If you prefer your message not be published, mark it "not for publication." Letters may be edited for length, context, and to match house style.
  PRIVACY: We don't collect personal information unless you explicitly provide it. For more details, see our Terms of Use.
  Low End Mac is an independent publication and has not been authorized, sponsored, or otherwise approved by Apple Inc. Apple, the Apple logo, Macintosh, iBook, iMac, eMac, iPod, iPhone, PowerBook, MacBook, MagSafe, Mac Pro, Apple TV, and AirPort are registered trademarks of Apple Inc. Additional company and product names may be trademarks or registered trademarks and are hereby acknowledged.

Custom Search

Navigation

Used Mac Dealers
Apple History
Video Cards
Email Lists

Favorite Sites

MacSurfer
MacMinute
MacInTouch
MyAppleMenu
InfoMac
Macs Only!
The Mac Observer
Accelerate Your Mac
RetroMacCast
PB Central
MacWindows
The Vintage Mac
   Museum
DealMac
DealsOnTheWeb
Mac2Sell
ramseeker
Mac Driver Museum
JAG's House
System 6 Heaven
System 7 Today
the pickle's Low-End
   Mac FAQ
Abandonware
   Petition
Mac vs. PC Info

Affiliates

The Apple Store
Mac Connection
B&H
MacMall
TechRestore
ExperCom
Crucial Memory
batteries.com

Advertise

All of our advertising is handled by BackBeat Media. For price quotes and advertising information, please contact at BackBeat Media (646-546-5194). This number is for advertising only.

Problems viewing this page with Internet Explorer 5.5 or 6? It works fine in other browsers, including IE 7. We recommend Firefox for those using Windows, as it is standards based and more secure than IE 6 (and earlier). More LEM visitors use Firefox than any other browser.