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Review: Newer Tech's MAXpowr G4/400 ZIF
G4 CPU Upgrade for AIO/Beige/B&W G3s
By Mike
Published: 12/10/99
Cache Control and Software Utility Features
Intro | Benchmarks | Appl. Tests | Software Controls | Installation | Specs/Design | Summary
Cache Control Software
Shortly after receiving the review sample, Newer Tech sent an updated v1.4b4 (beta) version of the MAXpowr G4 Control. I saw no problems of any kind despite the fact it was beta. Retail packages may ship with a later version.

The CD supplied with the review sample was a press kit version. The retail product CD may have other software besides the the Cache Control and GaugePro utility that are covered here.

Since the Newer Tech control software seems to provide an edge over the XLR8 version, I know readers will ask if it will work with other G4 upgrades. The answer is no. I thought I had spotted what looked like a SPD chip on the bottom of the MAXpowr ZIF, and apparently it is used for some sort of card ID. Attempting to use the Newer Tech software with the XLR8 G4 ZIF resulted in a warning box saying the Newer upgrade was not detected or working properly and that settings would not be saved.

As noted on the benchmarks page, the Newer Tech software shows improved memory bandwidth compared to XLR8's current offering. Many applications tests also showed a slight advantage for the Newer Tech G4. After the comment that G4 supervisor register settings were changed for compatibilty, I wondered if the Newer Tech software was sacrificing compatibility for memory performance. Although it's not possible for me to test all the hardware here in all combinations, I was glad to see that Retrospect backups via an Initio Bluenote SCSI card connected to an external SCSI Travan TR4 tape drive worked perfectly including verification. In the past Retrospect was the acid test for CPU upgrades, often reporting verification errors even when normal applications seemed fine. (The disabling of speculative processing put an end to these problems early last year).

MAXpowr G4 Cache Control
Cache Control

In line with Newer Tech's philosophy of simpler upgrades, the MAXpowr Control has only a few options and a single page. There are options to change cache speed, cache mode and a button to restore the default settings.

Since cache speed is far from a major factor in applications performance and cache overclocking can hurt stability, I always suggest you leave the cache setting at the default (usually 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 only other option in the MAXpowr Control is Cache Mode. Faster 'Write-back' (or Copy-back as it's often called) mode is enabled by default, with the slower 'Write-through' mode as an option. I never had the need to change the default mode and I consider it a troubleshooting option.

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. CPU power saving allows the CPU to go into low-power mode (reducing clock speed and perhaps even disabling the L2 cache as I remember) during extended periods of idle time. Personally, for a desktop machine I'd rather not have such things enabled.

About Cache Speeds:
Since backside cache speed is not a major factor in real-world application performance (CPU speed is), I don't recommend overclocking the cache as it can impact stability. The cache on this upgrade is rated for 200MHz by the manufacturer, and I left the settings at that selection.

I recently revisited the issue of cache speed by testing an iMac DV at 400/200 vs the stock 400/160. I saw zero gain in 3D games (which move a lot of data over the bus), even running 640x480 game modes to prevent the video chip from being the bottleneck. I saw a very small gain in applications, with only a 2 second reduction in a 5 minute Bryce2 rendering test. Although some owners swore they saw dramatic gains (from MacBench I suspect), I think if they were to actually run timed comparisons they'd see the benefit is very small in most cases. (When G3 CPU cards first arrived in late 1997, I thought a 1:1 cache speed was the holy grail.)

MacBench's CPU test is influenced by cache speeds far more than real world applications. Remember - a fast unreliable computer is lot less useful (and hazardous to your data) than a slow reliable one. I've pushed and tweaked most every Mac and upgrade I've ever owned (when possible), but don't sacrifice reliability by running on the razor's edge of stability.

Write-back (default) vs 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.

I'm not sure about the current Apple G4 systems, but the previous G3 models used 'Write-through' cache modes vs. the faster 'Write-back' mode. In my tests last year with a utility that would toggle these modes on an Apple G3, I saw very little gain from Write-back mode, at least in the Apple G3. Perhaps with the 66-100MHz memory bus speeds it's less of a performance issue than with older Macs that have a much slower memory bus.

Newer's Gauge Pro Utility:
The image below shows the details reported during the review tests in a B&W G3.

Gauge Pro Utility
Advanced settings page

Note the CPU stepping of the review sample was an early one - v2.2. Shipping models may be a later revision. (A Newer Tech G4 CPU card slot upgrade had a v2.6 CPU.) As shown on the Applications tests and Benchmarks page, CPU revision didn't seem to affect performance; in fact this 2.2 stepping G4 often outperformed the later 2.6 revisions (due to the Newer control software).

About Reported CPU Temperatures:
Although the 43C temperatures indicated with this upgrade are closer to reality than many I've seen, as I've mentioned many times in the past in the front page news and in the CPU ratings database; I don't believe the reported temperatures are 100% accurate as some G3 CPU upgrades often reported temperatures below ambient (impossible without active cooling). Many readers frequently ask if a specific C reading is too high. Most commercial CPUs are rated for 65C operation and if you have a temperature problem you'll know it quickly in my experience - as errors in the OS will occur almost immediately when a CPU overheats.

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

About Speculative Processing:
Since this topic has become the rage lately I wanted to mention this is not an issue for Apple Beige G3 and later systems which have ROMs that have no problems with speculative access/speculative processing (often called 'branch prediction'). What's interesting is that Apple's G4 Sawtooth system seems to have speculative processing disabled in the current version. In my older Mac tests, this resulted in a 4% drop in performance in most applications, but actually seemed to help Photoshop filters a bit based on PSbench tests.

Recent CPU card reviews here for older Macs cover this issue but I won't repeat it here as it does not apply to the systems upgraded for this review. (BTW: Apple 8600/250, 8600/300, 9600/300 and 9600/350 systems are also said to have 'G3 clean' ROMs. I can say my 9600/350 has run fine with Speculative Processing enabled with a G4 upgrade, but its recommended to run any pre-G3 system with speculative processing disabled if using a G3 or G4 CPU upgrade.)

Photoshop Altivec Enablers:
Despite some claims to the contrary, all G4 CPU upgrades I've tested take advantage of Photoshop 5.5's Altivec extensions. Until recently only Apple G4 systems had these extensions, but just as I was posting this review, Adobe publicly released an updated version which promised bug fixes and improved performance. I did see noticably better Lighting Effects filter performance as shown on the Application Tests page. Although XLR8 ships a Photoshop v3/v4 Altivec extension with their G4 CPU Upgrades, other vendors don't. Newer Tech felt that most owners of G4 CPU upgrades would already be using the latest version of Photoshop.

Summary: The software was easy to install and use. It worked well and in my opinion is the primary reason for slightly higher applications performance than any equivalent speed G4 CPU I've tested to date.

The next page describes installation of this upgrade in a B&W G3. Or you may use the links below to jump to a specific page.

Index of Newer Tech G4 400MHz ZIF Review

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

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