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Review: Newer Tech's iMAXpowr G4/433 CPU Upgrade
G4 CPU Upgrade for iMac 233 - 333MHz models
By Mike
Published: 7/19/2000
Cache Control and Software Utility Features
Intro | Benchmarks | Appl/Game Tests | Software Controls | Installation | Specs/Design | Summary
Cache Control Software

In past reviews comparing the Newer Tech G4/400Z (ZIF) to the XLR8 G4/400 - Newer's software provided an edge in performance. There's really no other G4 CPU upgrade to compare the iMAXpowr G4 to at this time (and I don't have a G3/466 iMac upgrade to test), but I'm confident their control software is one of the best on the market based on previous experience.

I saw no compatibility issues whatever during my tests and was glad to see my iMac Game Wizard (Voodoo2) 3D gaming card had no problems with the iMAXpowr G4. The Game Wizard is one reason many of us still hold onto rev A/rev B iMacs.

iMAXpowr G4 Cache Control
Cache Control

As you can see from the above image, my early review sample has a beta version of the Control Panel but I experienced no problems at all during use. I'm curious if the backside cache size settings will remain in the final version (perhaps allowing for a 512k Cache model?).

In line with Newer Tech's philosophy of simpler upgrades (and considering the iMac's focus on simplicity), the iMAXpowr Control Panel has only a few options and a single page. Unlike some CPU upgrades, there are no options to change cache speed or cache mode settings.

In reality, there is little to be gained in real-world performance from cache overclocking and it can destroy stability if pushed too far. I always suggest you leave the cache setting at the default (2:1 or 1/2 CPU speed). I never needed to change any of the default settings in over a week of use while performing tests for this review.

The Power Savings option present in Powerlogix and XLR8 cache controls is absent, but I suspect Newer relies on the Energy Saver Control Panel for this functionality or simply sets the modes automatically.

Based on discussions with Newer, the iMAXpowr defaults to Write-back (often called Copy-Back) instead of the slower 'Write-through' cache modes. 'Write-back' mode is faster as writes are written to the backside cache and later copied back to RAM. Write-through mode means that CPU writes are written immediately to much slower main system RAM.

Newer's Gauge Pro Utility:
The image below shows the details reported during the review tests of the iMAXpowr G4. As noted on the Benchmarks page, memory bandwidth reported by GaugePro increased more than 50% after installing the iMAXpowr G4 (from 60MB/sec to 90+MB/sec).

Gauge Pro Utility
GuagePro results with iMAXpowr G4

Note the CPU stepping of the review sample was v2.9, the latest shipping rev of the G4 as of this date.

About Reported CPU Temperatures:
The maximum temperature I saw during tests was 59C (most desktop G3s are rated for 65C, the G4 may be rated even higher as it is a higher wattage CPU).Many readers frequently ask if a specific C reading is too high. If you have a CPU temperature problem you'll know it quickly in my experience - as errors in the OS will occur almost immediately when a processor overheats.

As a side note, my PowerBook G3/250 (Wallstreet 1) has run 76C reported temperatures since day one with no adverse effects (the PB G3/500 I reviewed ran in the high 50's C as well). I suspect the PowerBook CPUs may be higher temperature rated parts however (I seem to remember reading 85C or 105C somewhere). Bottom Line is that if your CPU is running too hot the Mac OS will let you know very quickly.

About Speculative Access:
In case you're not aware, there are no issues of Speculative Access/Speculative Processing with later Mac models like the iMac. Just a comment in case anyone is not aware of it.

Photoshop Altivec Enablers:
Adobe released an updated version of the Photoshop 5.5 Altivec plugins which fixed bugs and improved performance from the first versions shipped with Apple G4 systems. See the Application Tests page for performance results. For a list of other applications that support Altivec (aka Velocity Engine).

The next page gives an overview of the installation of the iMAXpowr G4. Or you may use the links below to jump to a specific page.

Index of Newer Tech iMAXpowr G4 433MHz Review

Intro | Benchmarks | Appl/Game Tests | Software Controls | Installation | Specs/Design | Summary

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