Mac Musings

Low End G4: Migrating to an Older Power Mac

Dan Knight - 2009.07.06 - Tip Jar

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We're a bit less low-end at Low End Mac today, although we've migrated to an older Mac.

I've been using a dual 1 GHz "Mirrored Drive Doors" Power Mac G4 (from 2002) as my main production machine for several years. I bought it secondhand and slowly upgraded it from 768 MB of RAM to 2 GB, with larger hard drives, with a couple USB 2.0 cards, and with a 16x SuperDrive. The secondary SuperDrive (a 4x unit), CPUs, and Radeon 9000 graphics card remain the same.

For some time, I've been working from an external FireWire hard drive, on the theory that FireWire 400 may be a bit faster than the internal ATA bus and that it's easier to move everything to another computer in the even the MDD acts up if it's on an external drive.

Today I got to test that theory. Several times this morning I got the OS X gray screen of death. It's kind of warm, so it might be heat related. Or it could be a stick of RAM acting up. Or it might be something else completely.

Easier to switch computers than spend hours troubleshooting. Besides which, this would give me the chance to test some theories.

I have the good fortune to have three G4 Power Macs at Low End Mac headquarters. In addition to the 1 GHz dual MDD, I have a "Mystic" dual G4 upclocked to 500 MHz from 2000 (bought secondhand) and a "Digital Audio" (from 2001, donated) upgraded with a dual G4 from Giga Designs (also secondhand). Officially rated at 1.8 GHz, which overclocks the 1.42 GHz CPU by 26%, I've never been able to get it to run faster than 1.6 GHz. Still, that's 60% faster than my main Mac.

This morning I decided to run these three Power Mac G4 models through their paces, using conventional benchmarks and timing a few things I do regularly with a stopwatch. Each Mac was run from the same external FireWire hard drive, and the Radeon 9000 video card was moved from one machine to another. I also installed a 4-port Sonnet USB 2.0 card and connected everything (printers, hubs, etc.) as before.

Timed Tests

There were some differences other than CPU speed. Bus speed was slower as we moved to older Macs, and the MDD has more RAM than the other two. Here are the specifics and timed results (rounded off to the nearest second):

Model               Mystic     MDD     Dig Aud
CPU speed          500 MHz     1 GHz   1.6 GHz
L2 cache             1 MB    256 KB    512 KB
L2 speed           250 MHz     1 GHz   1.6 GHz
L3 cache             none      2 MB     none
L2 speed             n/a     500 MHz*   n/a
Installed RAM      1.25 GB    2.0 GB   1.25 GB
Bus speed          100 MHz   167 MHz   133 MHz
Startup to login   69 sec.   48 sec.   43 sec.
Login to Finder    42 sec.   31 sec.   46 sec.
Launch Classic     33 sec.   26 sec.   23 sec.
Open website       22 sec.   12 sec.    7 sec.
Total time        167 sec.  117 sec.  120 sec.

The Giga Designs upgrade has the biggest and fastest Level 2 (L2) cache, which should give it a real edge in raw processing power.

However, the Mirrored Drive Doors (MDD) has a high speed Level 3 (L3) cache, which I'm making an educated guess runs at 500 MHz and provided data to the CPU at three times the speed of motherboard memory. In addition, the MDD memory bus runs at 167 MHz - 25% faster than the 133 MHz bus in the Digital Audio (conversely, the DA has a 20% slower bus). This will give the MDD a big advantage when it comes to getting data from memory.

Startup and login aren't things I do often, usually a few times a week. Launching Classic is something I usually do once per startup, although if Classic is acting oddly, I will relaunch it. Opening the master site file (124 KB) in Claris Home Page 3.0 is something I do several times a day, averaging once for every new article we publish or update on Low End Mac.

Benchmark Programs

I also ran all three machines through our usual benchmark suite:

Let 1000 Windows Bloom

Let 1000 Windows Bloom draws 1000 windows to your screen as quickly as possible. Machines were tested using Mac OS X 10.4.11 "Tiger" and 10.5.7 "Leopard". Times are rounded to the nearest 1/10 of a second.

         Mystic   MDD    DA
10.4.11   27.5   13.4   14.0
10.5.7    39.9   16.4   24.3

The Mirrored Drive Doors wins this one, although by only 4.4%.

Power Fractal

This program creates a fractal pattern, which can really bog down a CPU. Results are reported in Mflops.

         Mystic    MDD     DA
10.4.11   3,411   8,565  13,290
10.5.7    3,322   8,470  13,220

The 1.6 GHz upgraded Digital Audio smokes the Mirrored Drive Doors with a 55% higher score.


Xbench has been out for some time. We used Xbench 1.3, which is calibrated so a 2.0 GHz Power Mac G5 scores 100.

10.4.11   Mystic   MDD    DA
Overall    24.0   50.4   56.3
CPU        30.2   54.3   86.3
Threads    39.1   71.8  114.2
Memory     21.6   38.4   28.4
Quartz     25.3   52.4   62.8
OpenGL     34.6   60.9   74.1
User Int.  11.0   53.2   48.4
Drive      36.8   59.3   53.5

The upgraded Digital Audio wins overall, although the Mirror Drive Door wins three benchmarks: Memory due to a faster system bus (167 MHz vs. 133 MHz), and User Interface and Drive could be due to the faster memory bus and L3 cache. Overall, the DA wins by almost 12%.

10.5.7   Mystic   MDD    DA
Overall    20.0   47.6   45.7
CPU        29.9   54.1   86.3
Threads    35.1   53.8   75.0
Memory     21.5   43.8   30.7
Quartz     24.6   61.5   65.7
OpenGL     34.6   54.4   64.5
User Int.   7.1   27.9   21.6
Drive      36.5   59.8   53.7

In a surprising upset, the 1 GHz Mirrored Drive Doors edges past the 1.6 GHz Digital Audio, but by barely 4%. The DA smokes the CPU, Threads, and OpenGL tests, while the MDD wins Memory hands down, does significantly better on User Interface, and edges out the Drive comparison by 11%.


Geekbench is a cross-platform benchmark that runs on PowerPC Macs, Intel Macs, and Windows PCs, making it possible to compare these old Power Macs to today's Intel-based Macs. Geekbench only tests the processor and memory systems, so drive performance isn't a factor and graphics should have minimal impact.

10.4.11    Mystic   MDD    DA
Overall      454    900   1218
Integer      524   1169   1673
Fl. Point    587   1026   1471
Memory       250    495    486
Streams      161    349    210

The 1.6 GHz Digital Audio wins by 35% overall, winning the Integer and Floating Point tests by 43%, losing the Memory test by less than 2%, and getting smoked on the Streams test.

10.5.7     Mystic   MDD    DA
Overall      460    943   1311
Integer      506   1117   1638
Fl. Point    632   1185   1784
Memory       226    485    454
Streams      170    406    235

Under Leopard, the upgraded DA wins by 39% overall - taking Integer by 46%, Floating Point by 50% while losing Memory by 6% and Streams by a huge margin.


Every benchmark gives us a different piece of the picture. For sheer processing power, the 1.6 GHz dual G4 wins hands down, but thanks to a faster system bus and a Level 3 cache, the Mirrored Drive Doors holds its own against a 60% faster CPU with a larger L2 cache.

In the best of all possible worlds, the Giga Designs upgrade would be able to achieve its claimed 1.8 GHz, boosting power by 12.5% - and the upgrade would be compatible with the 167 MHz system bus found in the faster Mirrored Drive Doors models (which would mean either 1.75 GHz or 1.83 GHz) and take advantage of the faster memory bus and L3 cache, in which case that machine would really scream.

Buying Advice

In terms of value, the best bet is probably a used 1.25 GHz Mirror Drive Door Power Mac with dual G4s, currently available for as little as $400 from used Mac dealers - and probably less on eBay and even less on Craigslist. Get the version that doesn't have FireWire 800 and does boot into Mac OS 9, and you'll have a 167 MHz system bus, a 4 GB L3 cache, Ultra ATA100 for internal hard drives, two optical drive bays, room for 2 GB of RAM, and no need to hassle with third-party CPU upgrades. It's the most powerful Mac that can boot the Classic Mac OS, and with its even bigger L3 cache, it could give my 1.6 GHz upgraded Digital Audio a real run for the money.

If you have access to a free or low cost accelerator, however, avoid the handful of G4 Power Macs that use a 167 MHz system bus. The ultimate Power Mac G4 to use with a CPU upgrade would be the Quicksilver and Quicksilver 2002 lines, which have a 133 MHz system bus, support up to 1.5 GB of RAM, work with "big" hard drives (over 128 GB), has two optical drive bays, and can take accelerators as fast as 2.0 GHz - if you can find them nowadays. Bang for the buck, the 733 MHz and 800 MHz single processor models are the ones to buy, as faster Quicksilvers have L3 caches that generally have to be removed when used with a CPU upgrade. These start at about $200.

For upgrading, I'm a huge fan of dual-processor systems if you're running any version of Mac OS X. Drawback is, a new dual-core upgrade will set you back $300 and up these days and may not offer any more performance than the Dual 1.25 GHz MDD at $100 less. However, if you have a low cost CPU upgrade option, these entry-level Quicksilvers can be your value choice.

It's all a matter of your needs, your plans, your wants, and your budget. There's a lot of life in these old G4 Power Macs, as they can boot into OS 9, support Classic Mode through OS X 10.4, and can run OS X 10.5 if you want to or need to.

I've been happily using G4 Macs since 2000 and remain very productive. I don't want to rip video on these machines, but for everything else I do, they are more than adequate. What more do you need?

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Dan Knight has been using Macs since 1986, sold Macs for several years, supported them for many more years, and has been publishing Low End Mac since April 1997. If you find Dan's articles helpful, please consider making a donation to his tip jar.

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