Mac OS X on a 7300 G3--How Fast Is It?

We previously installed Mac OS X v10.0.3 on an "unsupported" legacy Mac, a Power Mac 8500 with a 250 MHz 604e PPC CPU, using Ryan Rempel's Unsupported UtilityX. Mac OS X runs acceptably if slowly and is a bit unstable according to our tests posted here. The instability probably results from the low RAM, only 88 MB.

Next we installed Mac OS X on our 7300 which has been upgraded with an XLR8 G3 CPU clocked to 400 MHz and L2 cache at 160 MHz. It has 192 MB RAM. Again we used Ryan Rempel's Unsupported UtilityX to permit OS X to install. The 7300 was very slow initially, about the same as the 8500, because the G3's L2 cache on an unsupported legacy Mac is not enabled by Mac OS X. Fortunately, Ryan Rempel has a second trick up his sleeve called L2CacheConfig which enables the L2 cache. We installed Mac OS X, updated to v10.0.4 and enabled the L2 cache. Unlike with the Public Preview release of Mac OS X, the final version (at least 10.0.4) with Rempel's hack installed does not enable our L2 cache automatically on start up on our 7300. Each time after booting we have to enable the L2 cache manually with L2CacheConfig.

We ran our usual application launch test series with the couple of additions: launching Classic mode and scrolling Connectix's Virtual PC 4.0 Manual PDF in Adobe Acrobat 5.0. The results are listed in the table below. Shown in parentheses are the times for the 7300/G3 with the L2 cache disabled.

Average Launch Times in Full Seconds (No L2 Cache in parentheses)

Application	7300 400 MHz G3	G4 Cube 450 MHz
Classic Mode	60 (212)	40
Netscape 4.77	5 (12)	4
Word 2001	-	2
Scroll in Acrobat 5 (1/4 file)	47 (81)	17*
AppleWorks 6.1b	9 (27)	6
I' Explorer 5.1.1	11 (28)	9
-OmniWeb 4.0.1	13 (40)	10
Mail	7 (15)	7
System Preferences	4 (6)	3

*Prorated for comparison from a complete file scroll.

There are several observations worth mentioning. First, enabling the L2 cache makes a world of difference. The 7300 with a 400 MHz G3 but with L2 cache disabled is not much faster than the 8500 with a 250 MHz 604e CPU. However, with L2 cache enabled the 7300 G3 whizzes along nearly as fast as our 450 MHz G4 Cube. The one exception being graphics intensive operations like the scrolling test where the file that was scrolled contains numerous images. This is because we had to use the built-in motherboard graphics subsystem of the 7300 rather than a graphics accelerator PCI card. The only ones we have with a PCI slot interface are 3dfx Voodoo cards which Mac OS X does not support as of yet and may never. We hope that the 3dfx cards will be supported in the future since the Voodoo5 with its Glide drivers, in our opinion, still produces the best visual images in our favorite 3D shooter, Unreal Tournament (especially the Deck 16][ and Peak Monastery maps), if not the fastest. Surprisingly, our 8 MB VRAM ATI XClaim Rage Pro (not the Rage 128 Pro) card did not work either.

The bottom line is that a G3-upgraded 7300 of 400 MHz or more with 192 MB RAM and a supported graphics card like an ATI Radeon PCI card should run Mac OS X very well.