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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, 10:39:10 PM »any of the PCI gpus of the time didnt really saturate the full pci bus anyway
That is a very sharp observation. You are absolutely right—for the Power Mac G3 B&W era, the GPU was rarely the component choking the PCI bus; it was almost always the storage I/O.
Why the GPU didn't saturate the bus
The "3D Accelerator" Role: In 1999–2002, cards like the Radeon 7000 or GeForce 2 MX weren't "engines" in the modern sense. They mostly processed what the CPU sent them. Since the 100MHz system bus of the G3 was already a bottleneck, the CPU couldn't feed the GPU data fast enough to actually fill a 266 MB/s (66MHz) or even a 133 MB/s (33MHz) pipe.
Asset Sizes: Textures and geometry data for games of that era (like Quake III or Unreal Tournament) were tiny—often measured in kilobytes or a few megabytes. They didn't require massive "burst" bandwidth to load into the card's VRAM.
Why the Storage Swap works so well
By moving the SATA card into that 66MHz slot, you are giving the "hungriest" component the widest path.
Audio Streaming: Unlike a GPU, which loads a scene and then works locally, a DAW (Digital Audio Workstation) is constantly "pulling" data from the drive.
Zero Latency: Moving the GPU to the slower 33MHz slot has almost zero noticeable impact on your UI or 2D performance in OS 9 or OS X, but moving the SATA card to the 66MHz slot can literally double your track count before the disk buffer underruns.
In short, you’re effectively "trading" bandwidth that the GPU wasn't using anyway to solve the biggest performance hurdle in the entire machine.
Are you using a PCI SATA card with the Silicon Image chipset, or are you looking at a Sonnet Tempo card?
That is a very sharp observation. You are absolutely right—for the Power Mac G3 B&W era, the GPU was rarely the component choking the PCI bus; it was almost always the storage I/O.
Why the GPU didn't saturate the bus
The "3D Accelerator" Role: In 1999–2002, cards like the Radeon 7000 or GeForce 2 MX weren't "engines" in the modern sense. They mostly processed what the CPU sent them. Since the 100MHz system bus of the G3 was already a bottleneck, the CPU couldn't feed the GPU data fast enough to actually fill a 266 MB/s (66MHz) or even a 133 MB/s (33MHz) pipe.
Asset Sizes: Textures and geometry data for games of that era (like Quake III or Unreal Tournament) were tiny—often measured in kilobytes or a few megabytes. They didn't require massive "burst" bandwidth to load into the card's VRAM.
Why the Storage Swap works so well
By moving the SATA card into that 66MHz slot, you are giving the "hungriest" component the widest path.
Audio Streaming: Unlike a GPU, which loads a scene and then works locally, a DAW (Digital Audio Workstation) is constantly "pulling" data from the drive.
Zero Latency: Moving the GPU to the slower 33MHz slot has almost zero noticeable impact on your UI or 2D performance in OS 9 or OS X, but moving the SATA card to the 66MHz slot can literally double your track count before the disk buffer underruns.
In short, you’re effectively "trading" bandwidth that the GPU wasn't using anyway to solve the biggest performance hurdle in the entire machine.
Are you using a PCI SATA card with the Silicon Image chipset, or are you looking at a Sonnet Tempo card?
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