G4 upgrade cards - tested and rated

Introduction

Apple doesn’t seem to like beige. The public doesn’t seem to like beige. You may not like beige. But if you have a beige Mac on your desktop, you might want to consider upgrading it rather than going graphite. The latest G4-upgrade cards are surprisingly stable, and bring an older Power Mac’s performance close to that of new Macs. With prices ranging from £425 to £600, G4 upgrades aren’t cheap, but many users – particularly those with lots of peripherals – will find them a cheaper alternative to new 400MHz G4 systems, which start at £1,099.
What we tested
Macworld Lab took a look at all the US-made G4 processor slot upgrade cards, in both 350MHz and 400MHz configurations: Newer Technology’s MAXpowr G4, Powerlogix’s PowerForce G4, Sonnet Technologies’ Crescendo G4 PCI, and XLR8’s Mach Carrier G4. These upgrades work by replacing the Mac’s original CPU with a new one driven by a G4 processor. They’re for use in the Power Macintosh 7300, 7500, 7600, 8500, 8600, 9500, and 9600; the DayStar Genesis and Millennium; the Power Computing PowerTower Pro and PowerWave; and the Umax. The big difference between a G4 processor and a G3 processor is that the G4 uses AltiVec – called Velocity Engine by Apple. AltiVec offers a major speed boost, but only to applications that take advantage of it – most notably multimedia and graphics software. In addition, not all software has been optimized to derive a performance benefit from the G4 processor – to see a list of software currently optimized for the G4, go to www.macworld.co.uk/upgrades. If the applications you commonly use aren’t on that list, you may want to consider getting a G3 upgrade for your Mac instead – a G4 upgrade won’t give you much of a boost. All the G4 slot upgrades we tested delivered similar performance – not surprising, since they’re all based on the same processor. What is remarkable about the upgrades is how close they come to matching the performance of new G4 machines. In most of our tests, each upgrade running in a Power Mac 7300 was nearly as fast as a graphite G4 with the same processor speed.
Not up to it
Surprisingly, the only time the upgraded 7300 lagged noticeably behind was when we ran the Quake III tests – though, to be fair, the upgrades were running in a machine that previously played Quake III only grudgingly. All sophisticated computer processors use a technique called speculative processing – moving data they think they will need into the cache – to improve overall performance. The G4, since it usually runs four or more times as fast as the system bus, has a lot of time to speculate. Getting a G4 upgrade to work in an older Mac means adding a bit of code to the Mac’s open firmware – data stored on your Mac that controls some of its most basic functions – to prevent the new processor from making catastrophic mistakes while speculating. Newer Technology’s upgrades have a ROM chip that contains this data – when the upgrade starts up, it puts the data into the Mac’s open firmware. All the other upgrades take a software approach, requiring code to be added to your Mac’s open firmware from a floppy disk when the upgrade card is installed. The problem with the software approach is the added code can be deleted accidentally by zapping the PRAM. If this happens and your Mac refuses to start up, remove the upgrade and reinstall the original processor, then run the open-firmware updater again, and finally reinstall the upgrade. If you remember to hang on to your old processor and the firmware floppy, then buy the least-expensive G4 upgrade – if you’re likely to forget, go with a Newer card.
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