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Mac OS 9 (Oct 1999) / Re: switching the gpu 66mhz slot w disk io card to improve sata bandwidth for SSD
« Last post by chrisNova777 on April 09, 2026, 10:45:22 PM »"so a Powermac g3 B+W booting off a SIL3112 card in a 66mhz slot is superior to any g3 or g4 with any sil3112 card installed anywhere else because it will only run at 33mhz"
Exactly. You’ve hit on the "secret weapon" of the B+W G3 and YIKES G4!!!
Ironically, because Apple moved the graphics to a dedicated AGP slot starting with the G4 "Sawtooth," they actually downgraded the storage potential for anyone using a PCI SATA card.
The "G3 Advantage"
The G4 Limitation: In a Power Mac G4 (Sawtooth through MDD), all the PCI slots are clocked at 33MHz. Even if you put a SiL3112 in a G4, it is capped at that ~33–45 MB/s real-world ceiling.
The G3 B+W Exception: By "sacrificing" the high-speed graphics slot and moving your GPU to a slower slot, you are the only one who can give that SiL3112 a 66MHz path. This allows you to hit that ~65 MB/s sweet spot [previous turn]—roughly 50% faster than a G4 using the same card.
The Only Exception: The G4 Quicksilver/MDD 64-bit Slots
There is one technical "asterisk": some later G4 models (like the Mirror Drive Door) have 64-bit PCI slots, but they still run at 33MHz. It wasn't until the Power Mac G5 that 66MHz (and 133MHz PCI-X) slots returned for general use.
Why this is the "Ultimate" OS 9 Audio Rig
For a Mac OS 9 build, your specific configuration—B+W G3 + SiL3112 in the 66MHz slot—is arguably the highest-bandwidth storage setup possible. A G4 might have a faster CPU for processing plugins, but your G3 will actually have a "wider" pipe for streaming those high-track-count audio files from disk.
It makes the B+W G3 a very unique "bottleneck-breaker" for vintage studio work.
Are you planning to use a SATA SSD to ensure you're completely maxing out that 66MHz bandwidth, or a high-RPM mechanical drive?
Exactly. You’ve hit on the "secret weapon" of the B+W G3 and YIKES G4!!!
Ironically, because Apple moved the graphics to a dedicated AGP slot starting with the G4 "Sawtooth," they actually downgraded the storage potential for anyone using a PCI SATA card.
The "G3 Advantage"
The G4 Limitation: In a Power Mac G4 (Sawtooth through MDD), all the PCI slots are clocked at 33MHz. Even if you put a SiL3112 in a G4, it is capped at that ~33–45 MB/s real-world ceiling.
The G3 B+W Exception: By "sacrificing" the high-speed graphics slot and moving your GPU to a slower slot, you are the only one who can give that SiL3112 a 66MHz path. This allows you to hit that ~65 MB/s sweet spot [previous turn]—roughly 50% faster than a G4 using the same card.
The Only Exception: The G4 Quicksilver/MDD 64-bit Slots
There is one technical "asterisk": some later G4 models (like the Mirror Drive Door) have 64-bit PCI slots, but they still run at 33MHz. It wasn't until the Power Mac G5 that 66MHz (and 133MHz PCI-X) slots returned for general use.
Why this is the "Ultimate" OS 9 Audio Rig
For a Mac OS 9 build, your specific configuration—B+W G3 + SiL3112 in the 66MHz slot—is arguably the highest-bandwidth storage setup possible. A G4 might have a faster CPU for processing plugins, but your G3 will actually have a "wider" pipe for streaming those high-track-count audio files from disk.
It makes the B+W G3 a very unique "bottleneck-breaker" for vintage studio work.
Are you planning to use a SATA SSD to ensure you're completely maxing out that 66MHz bandwidth, or a high-RPM mechanical drive?
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