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Review: Giga Designs G4 1.25GHz CPU Upgrade
By Mike
Published: 3/14/2003
= Links to Review Topics Pages =
Intro | Benchmarks  | Apps Tests | Game Tests | Installation | Specs/Design

Pros: Ran reliably at 1.33GHz in my Digital Audio G4 Tower (w/o any voltage change). Compact upgrade w/copper heatsink and attached fan is easy to install. Usually lower priced than the competition. Adjustable speeds via jumpers (see specs page for notes and jumper settings). No software required for L3 cache enabling.

Cons: Wake from sleep problem in OS X (not in OS 9) in my DA system at 1.33GHz, but not at 1.26GHz. I verified that my problem with waking from sleep were not seen at 1.26GHz in tests with both OS X 10.1.5 and 10.2.4. (At 1.33GHz with the default 5:1 CPU/L3 ratio, the L3 cache bus is running 266.6MHz, the spec limit of this 7455A CPU chip according to my talks with Giga Designs about this issue. I've not tried using 3rd party software to reduce the L3 cache speed with the CPU at 1.33GHz yet.) I don't usually sleep my Towers personally, only Powerbooks but noting this for those that do. (Note - one of the reports in the Rate Your CPU Upgrade database for this upgrade noted he did not have the problem - so my results may not be typical.)

Compatibility: PowerMac G4 Sawtooth, Gigabit, Digital Audio and Quicksilver 2001/2002 Towers. (Note: Reportedly due to a system firmware issue - this upgrade is limited to 1.2GHz speeds (max) in the 2002 Quicksilver model.)


I really like the adjustable/compact Giga Designs CPU upgrades since testing their previous models (G4/1GHz and G4/800) that I reviewed in January. Giga Designs recently provided a review loaner of their latest model - a 1.25GHz (sold as a "1.25-1.33GHz") for testing in my Digital Audio Dual G4/533 Tower System. For full details on the test system's hardware and software, see the system details listing below. The Giga Designs upgrades are compatible with G4/AGP towers from the original AGP "Sawtooth" up to the Quicksilver 2002 models. (For these new 1.25GHz/7455A CPU based upgrades, speeds in Quicksilver 2002s are limited to 1.2GHz they say due to a QS2002 firmware issue.)
As I said in my previous review, I really like their compact design with attached copper heatsink/fan and easily adjustable settings. Unlike their G4/800 and 1GHz models I tested in this Digital Audio system, I did see an OS X wake from sleep problem with this sample. That's not a show-stopper for me since I generally only sleep my PowerBooks, but since some readers do sleep their desktops, I wanted to point this out. Otherwise the 1.25GHz upgrade (running at 1.33GHz) was fast and totally stable in extended use in this system. Performance varies by application/game/benchmark and can be affected by other components like graphics card and hard drive - see the later pages of this review for test results. In some cases like converting a very large QT movie to MPEG4 and iMovie exports, the 1.33GHz was about twice as fast as my Dual 533 and faster than a MDD dual 1GHz in those tests (iMovie and QT didn't seem to take advantage of dual CPUs - iTunes MP3 encoding does however). To see what others thought of their Giga Designs (or other brand) of CPU upgrade - you can search the Rate Your CPU upgrade database here.

This review compares the performance of:

  • An original Digital Audio (DA) G4/533 Dual CPU
  • The DA system w/Powerlogix dual 1GHz upgrade
  • The DA system w/Giga Designs 1.25GHz (7455A w/2MB L3 cache) set to 1.33GHz
  • The DA system w/Giga Designs G4/800 (7451 with no L3 cache)
  • The DA system w/Giga Designs 1GHz (7455 CPU w/2MB L3 cache)
  • The DA system w/Giga Designs 1GHz model set to 800MHz (to compare 800MHz w/L3)
  • A Mirror Drive Door (MDD) Dual 1GHz G4 system

I no longer own any of the older G4 towers to use as test beds, but owners of older AGP towers can run tests described on the review pages to compare their performance to these upgrades.

Since the Giga Designs CPU upgrades are adjustable and it was sold as a 1.25-1.33GHz upgrade, I ran all tests set to 1.33GHz. Giga Design commented that they no longer consider Overclocking as "abuse" warranty-wise, as long as the core voltage isn't increased. See the specs page for notes on switch settings. (Of course YMMV, and there's no guarantee on short or longterm reliability when overclocking. Case cooling can also affect max reliable speeds.)

CPU Upgrade pricing can change at any time, but as of March 14th, 2003, site sponsor OWC sells the "1.25-1.33GHz" Giga Designs upgrade on the site specials page for $599. (Update - as of May 15th, 2003, the the site specials page price was $545. Always check the site specials page for the current pricing after the review date.)

Review Table of Contents:

  1. Applications Performance: Tests with QT to MPEG4 conversion, iMovie2 (OS X) quicktime movie export, iTunes3 MP3 encoding, multitasking, and Photoshop 7.0 (50MB image/21 filter tests).

  2. Games Performance: Tests with Quake3, Unreal Tournament X, and Return to Castle Wolfenstein.

  3. Benchmark Performance: Altivec Fractal demo, CineBench 2003 and Cinebench 2000 test results.

  4. Installation: Comments on installing the upgrade, photos of it installed, etc.

  5. Specs/Design: Details of the upgrade's CPU and Cache. Includes jumper setting info.

System Compatibility:
The Giga Design CPU upgrades are listed as compatible with the following Mac models:

  • Apple G4/AGP "Sawtooth"
  • Apple G4/AGP "GigaBit Ethernet"
  • Apple G4/AGP "Digital Audio"
  • Apple G4/AGP "Quicksilver"
  • Apple G4/AGP "Quicksilver 2002" *

* Max 1.2GHz speeds in 2002 QS models currently.

    OS Requirements:
  • OS 9.2.1 or OS 9.2.2
  • OS X

Other Owner Experiences: For owner ratings of most every CPU upgrade for any upgradeable Mac, search the Rate Your CPU Upgrade database.

Test System Details:

  • Apple Digital Audio G4 Tower
  • Dual 533MHz G4 CPUs (7410) w/1MB SDR L2 cache per CPU
  • 133MHz (SDR) bus w/1GB RAM
  • Western Digital WD120JB 120GB (20% free space) Hard Drive w/OS 9.2.2 and 10.2.3 installed
  • Onboard ATA/66 hard drive controller
  • Pioneer OEM DVR-103 Superdrive
  • Retail ATI 8500 AGP 64MB graphics card
  • Quicktime 6 (Pro)
  • Virtual Memory Disabled in OS 9
  • Airport active for all tests

For comparison to a new Mac, the following system was used:

  • Mirrored Drive Door G4 tower
  • Dual 1GHz (7455 rev 2.1) CPUs with 1MB DDR L3 cache per CPU
  • 167MHz bus (SDR) with 768MB DDR memory
  • OEM IBM 80GB drive (60% free space) w/10.2.3 and 9.2.2
  • Onboard ATA/100 hard drive controller
  • OEM ATI Radeon 9000 Pro 64MB graphics card
    (Cinebench 2003 tests included ATI 8500 AGP and Nvidia GeforceTI results)
  • OEM Pioneer DVR-104 superdrive
  • Quicktime 6.1 (Pro)
  • Airport active for all tests

Display used was a Sony 19" F400. The hard drive was not optimized. For MP3/CD rip tests, a Lite-on 40125S (40x12x48x) CDRW in a Pyro Firewire case was used.

You can follow my preferred path through the review by continuing to the next page, or use the links below to jump to a specific page.

Index of Giga Designs CPU Upgrade Review Pages

Intro | Benchmarks  | Apps Tests | Game Tests | Installation | Specs/Design

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