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InfoHQ - Apple Power Mac G4 vs Pentium III

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Apple Power Mac G4 - Pentium III PC Face-off
Which System is Faster?

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Article Index
Comparing Apples and Oranges
The Brains - G4 and Pentium III Coppermine
Getting the Picture - Video Speed
On the Road to The CPU - RAM and Bus Speed
Other Noteworthy Power Mac Features
Which Platform is the Winner?

Apple Power Mac G4
Photo Courtesy of Apple

Comparing Apples and Oranges

Apple had to go and do it. Not content with upping the speed of the Power Mac G4 to 500 MHz, they had to take on the fastest Intel Pentium III. They claiming on their web site that the 500 MHz G4 processor is twice as fast as the Intel Pentium III 800 MHz processor.
While I had always thought that the G4 was an advanced processor, I couldn't believe that there was that much difference in the performance of the two CPUs. Especially since the Pentium III 800 Coppermine CPU has almost twice the clock speed of the 500 MHz G4.
And does it stand to reason that if an Apple Power Mac G4 computer has a faster CPU, does that mean that the entire system is actually faster than an 800 MHz Pentium III based system? Should PC users throw up their hands in despair and run out and buy a Mac? Is it even possible to compare computer systems which use entirely different operating systems?
Well fear not dear reader, we decided to don our steel shorts and jump into one of the most hotly contested questions since the PC was invented. We're going to examine the "guts" of the Apple Power Mac G4 computer and compare it to a typical Intel Pentium III 800 MHz system piece by piece.

The Brains - G4 and Pentium III Coppermine

So which CPU is really faster? How did Apple decide that its 500 MHz G4 was twice as fast as the Pentium III 800?
Apple used speed tests Intel performed on the Pentium III 400 and compared them test for test against its G4 500 (table at bottom of Apple's page). The Apple tests were averaged and Apple concluded that the G4 was 3.52 times as fast as a Pentium III 400 and then did some kind of clock speed adjustment and decided that the G4 was 2.2 times as fast as the Pentium III 800.
Now that bone kind of stuck in our throat and made us wonder how Apple could leap from a test that was 3.52 times as fast as a 400 MHz Pentium III to being twice as fast as a Pentium III 800. As a matter of fact, the Pentium III 400 and the Pentium III 800 are two different CPUs. The Pentium III 400 had a half speed 512K L2 cache and a bus speed of 100 MHz -- compared to the 800 MHz Pentium III's 256 KB full speed cache and 135 MHz bus speed. So we decided to try to make a better comparison.
We poured though Intel's tests and we could not find similar tests that were performed on the 800 MHz Pentium III (which is probably the same problem Apple had). So we settled on Intel's iCOMP test page which compares the Pentium III at various speeds. Unfortunately, the Pentium III 400 is not listed so we extrapolated a value. We used the iCOMP speed difference between the 500 MHz and 600 MHz Pentium III (1930 -1650 = 280) and subtracted it from the 500 MHz iCOMP of 1650 and arrived at an estimated Pentium III 400 iCOMP of 1370 (1650-280). The Pentium III 800 has an iCOMP of 2690 which is about twice as fast as our estimated Pentium III 400 iCOMP of 1370 (2 x 1370 = 2740).
In conclusion, based on our estimates it appears that in raw processing power, the G4 is about 1.76 times as fast as the Pentium III 800 and is indeed the faster consumer CPU in production. Again, our speed difference is an estimated amount, and it is too bad that an actual speed comparison between the two CPUs has not been made (of course that may be by design of the CPU manufacturer's). If the CPU was the only part of the computer that mattered, we would stop here and recommend everyone go out and buy a G4 -- but there's more to a computer than the CPU.

Motorola MPC 7400 (G4)
Photo Courtesy of Motorola


Processor Specs
  G4 Pentium III
Clock Speed 500 MHz 800 MHz
L2 Cache 1 MB, half speed 256 KB, full speed
Bus Speed 100 MHz 135 MHz
Data Read 32 bit 32 bit
Speed Compared to Pentium III 400 MHz 3.52 times as fast (per Apple) 2.00 times as fast (InfoHQ estimate)
Compared to Pentium III 1.76 times as fast  

Intel Pentium PIII

Intel Pentium PIII
(Photo Courtesy Intel Corporation)

Getting the Picture - Video Speed

Round one went to the G4 and its faster processor, but what about high-end video speed? The type and speed of the graphics adapter is very important for any kind of graphics intensive tasks including 3D modeling, games, CAD programs, and other video applications.
The G4 has a 2X AGP port and uses the ATI RAGE 128 PRO graphics card. This card features an 8 million triangles/second setup engine which puts it in the same speed range as the RIVA TNT2 and the Voodoo3 cards used on PC computers. This is a capable graphics card system however, it is a generation behind what is available in high end PC systems.
Pentium III 800 systems will typically use the Camino 820 chipset, it features a 4X AGP port and it will typically be paired with a NVIDIA GeForce 256 graphics cards. The NVIDIA GeForce 256 card delivers 15 million sustained polygons/triangles per second which makes it roughly twice as fast in graphics intensive applications as the video card in the G4. < For more information on the discussed video cards, see our article 3D Video Card Roundup.>

Video Card Specs
G4 Pentium III 800
Video Card ATI RAGE 128 PRO NVIDIA GeForce 256
Video Port 2X AGP 4X AGP
Speed 8 million triangles/second 15 million triangles/second
Speed Comparison   1.875 times as fast in high end graphics

On the Road to The CPU - RAM and Bus Speed

Round 1 went to the G4, and round 2 went to the Pentium III 800 with almost twice the high-end graphics speed. Our last area of comparison is the RAM and Bus speeds of the two computers.
RAM speed and throughput is very important because RAM bottlenecks will cause CPU "wait states" to occur (a period when the CPU sits idle waiting for information). A high speed bus is important because the CPU communicates to system RAM over the bus. A slow system bus will also result in wait states.
Apple's G4 uses PC100 SDRAM and has a 100 MHz bus speed. The Pentium 800 with Camino chipset uses 600-800 MHz Rambus DRAM and has a 135 MHz bus. As Rambus DRAM has double the peak bandwidth of PC100 SDRAM (1,600 Mbps vs. 800 Mbps), the PC system should have less frequently induced wait states and more efficient memory usage.

RAM and Bus Speed
Power Mac G4 Pentium III 800
Bus Speed 100 MHz 135 MHz
RAM Type PC100 SDRAM Rambus DRAM
Ram Speed 100 MHz 600-800 MHz
Peak Bandwidth 800 Mbps 1,600 Mbps
Throughput Comparison   Twice as efficient

Other Noteworthy Power Mac Features

The Power Mac G4 does have a few other nice features that are not typically found on a PC: Airport Technology and an IEEE Firewire port.
AirPort Technology centers around a wireless base station device. Macs can be up to 150 feet away from a Base Station, and the wireless data rate is up to 11 megabits per second. The nice part is that several Macs can use the same base station to connect to the Internet.
IEEE 1394 Firewire is a multimedia serial bus standard that is about 40 times as fast (400 Mbps) as the current universal serial bus (USB). It is mostly used to connect to video cameras or other high speed devices like external hard drives. (Some Sony computers feature Firewire).

Which Platform is the Winner?

What conclusions can be reached from the above analysis? We know that the 500 MHz G4 processor is without doubt the fastest CPU in a consumer computer today. However, we also have shown that the PC platform has available graphics cards that are almost twice as fast as the Power Mac's and the PC memory throughput is twice as efficient. So which system is really faster?
Probably the answer to that question is -- it depends. It depends on what software applications you intend to run on your computer. If you seldom use high-end graphics then the Power Mac would certainly be the faster system. If you are an avid 3D game player, then the Pentium III 800 would be the better choice. Then again, some of you may have no choice as your software will only run on one of the platforms.
In the end, we have to declare both platforms as winners (despite our steel shorts), as each system is advancing computer technology.

Comparison Summary
Power Mac G4 Pentium III 800
Processor Speed 1.76 times as fast  
High-end Graphics Speed   1.875 times as fast
RAM throughput   Twice as efficient
Noteworthy Mac Features AirPort, Firewire  

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