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Accelerate Your Mac! - the source for performance news and reviews
The Source for Mac Performance News and Reviews
Review: Powerlogix's 7447A & 7457 CPU Upgrades
(Single and Dual CPU - 1.2GHz to 1.8GHz)

Tests in Quicksilver G4/733
By Mike
Published: 7/1/2005
Updated: 8/9/2005 (for 1.7/1.8GHz models)
CPU Director 2.1 Software
Intro | Benchmarks  | Apps Tests | Game Tests | Installation | Specs/Design
 


This page has info and screenshots on Powerlogix's CPU Director 2.1. In general I don't like installing any software that isn't necessary (unlike older Mac CPU upgrades, those for G4 towers don't usually need any cache enablers, etc.). Like any 3rd party app or driver, it's also one more thing that can require updating when Apple releases an OS X update (as many of you already know from experience). However for these Dual CPU upgrades, Powerlogix said it was 'required' for power management reasons (although they do run without it, there are benefits to having it installed that will be covered below)

CPU Director 2.1 DFS (Dynamic Frequency Switching) can be a nice bonus feature for owners of 7447A CPUs (also possible with 750FX/GX and 7448's). It can be enabled or disabled via CPU Director's options tab, but DFS can only be enabled if the bus multiplier is an integer number. I.E. for the 1.8GHz model in a 133MHz bus mac it can't be enabled as the multiplier is 13.5x, but for a 100MHz bus system the multiplier would be 18x and DFS could be used. All tests here of the Dual 1.7GHz (running at 1.73GHz in the QS) had DFS enabled as it was using a integer (i.e. 13x) bus multiplier. As with all brands I know of - all the (higher speed at least) 7447A CPU upgrades are overclocked. (For example 1.6GHz rated CPUs used in 1.8GHz models and 1.42GHz rated CPUs and 1.7GHz model samples in this review for instance.)
(NOTE: For OS X Tiger (10.4.x), each Tiger OS update has broken the current version of CPU Director and required an update to CPU Director to work with the Tiger update.)
Unlike older G3 and G4 series PowerPCs, the 7447A (and 750FX/GX) CPU models can have their bus multiplier changed via software on-the-fly.
I didn't realize that CPU Director was -required- (per PL), since the CPUs are recognized, caches enabled, etc. without it. I didn't use CPUD for the earlier tests of the Dual 1.2GHz models, but did install it for the later tests of the 1.7-1.8GHz models. (I ran some 100% CPU load 24hr stress tests without it.) Here's a clip from an email with Powerlogix's Robert Jagitsch on the subject:

" CPUD (CPU Director) 2.1 has the power management software built in, so it's really required on dual cpu machines. Even at 100% load, the power draw drops about 7-8% with CPUD 2.1. At moderate loads power drops substantially. This extra margin is important, it can be the difference between a frozen app, and continuous operation.
-Robert Jagitsch
Powerlogix "

Note that OWC (who later bought Powerlogix) now states that CPU Director is not required to run these upgrades, but is required if you want to see the Powerlogix's onboard temperature sensor readings or use the DFS feature of course. I really didn't expect to like DFS but I did. It helps lower temperatures and reduce power use when the CPU isn't heavily loaded and was responsive (quickly jumped to full CPU speed when needed).


Below are screenshots of the various tabs/panels in CPU Director 2.1. They were taken while running the Dual 1.73GHz 7447A upgrade with DFS enabled, so any screenshots taken with the CPU idle show the reduced (by 1/2) CPU and (onchip) cache speed as noted.

System Profile tab
CPUD Profile tab

The images here are all with DFS enabled, but the above image was taken with the CPU under load (full CPU speed selected) - the image below is with DFS enabled and CPUs not under load (CPU speed cut in half to save power/reduce heat.)
Although even saving a file from Grab caused the CPU speed to kick up immediately to full speed, just playing a song in iTunes didn't. A Pismo owner (w/PL G3/900 upgrade) recently commented in the news page on DFS and lower temperatures with that upgrade, saying he thought that a 50% CPU load was a trigger to kick the CPU up to full speed. I asked Robert about the trigger level:

" The load/activity is controlled by Apple's code that is in Energy Saver. We just enable things so that the Energy Saver daemon can control DFS functionality on 7447 and 7448 CPUs. We're not sure what Apple's trigger is.

(DFS and on-board thermal sensor)... are exclusive to Powerlogix upgrades. ...these really look at first glance to be minor features, but they really aren't.
-Robert "

DFS works like Apple's Energy Saver "automatic" performance option on later Mac models. I was originally concerned that DFS would significantly hurt performance in the apps/game tests but as you can see from the results on those performance test pages here, it didn't seem to. You can also disable DFS of course but I was impressed how well it worked and it could really be a plus for some systems - especially Cubes and upgraded Powerbooks.
DFS can be enabled or disabled via CPU Director's options tab (see below), but it can only be enabled if the bus multiplier is an integer number. I.E. for the 1.8GHz model in a 133MHz bus Mac it can't be enabled - as the multiplier is 13.5x. But for a 100MHz bus system the 1.8GHz upgrade's multiplier would be 18x and DFS could be used.


System Profile tab (DFS enabled/CPU not under load)
DFS enabled


All the new model PL upgrades have an on-board temperature monitoring feature. CPU Director reports this temperature as well as showing a graph of tempeature over time.

Thermal Tab
thermal tab

The above is just an example taken during idle periods. In the 100% CPU load/stress test with the dual 1.8GHz upgrade, temperature ramped up to about 66°C max within the first hour and remained at that level for the duration of the test. No problems were seen during the stress test with any of the CPU upgrades using the new heatsink. I used these upgrades for more than a month. (I don't like to just post a quick series of test results, even though that takes a lot less time to do and it's all that some care to see.)


In addition to DFS, the Options tab also has settings for enabling/disabling "Speculative Access" which generally is only disabled if you're running a CPU upgraded legacy (pre-G3) PCI Mac. (Disabling it on cpu upgraded older macs was a fix for some problems first reported many years ago here.)

Options tab
Options

All tests here of the Dual 1.7GHz (running at 1.73GHz in the QS) had DFS enabled. None of the other upgrades used for comparison had DFS enabled.


The L2 Cache tab shows the current cache speed, size, type, etc. and has options to disable it but normally you'd never do that of course unless troubleshooting a suspect CPU perhaps.

L2 Cache tab (DFS enabled/CPU not under load)
L2 cache

Again the screenshot above was taken with DFS enabled and the CPUs not under load. (The CPU speed would quickly change to 1.73GHz otherwise.)


And finally (just for the record) here's the Info tab which has a link to the PL website.

Info tab
Info tab




Index of PL 7447A/7457 CPU Upgrades Review Pages

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

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