recently got an original pci-424 5v pci card, remember this card will work on any G4/G3 mac but not a G5 or anything above that
For Mac OS 9:
PowerPC G3 CPU 500 MHz or faster; Power PC G3 or faster recommended
128 MB RAM; 512 MB or more recommended
Mac OS version 9.0 to 9.2.2
Available PCI slot
Large hard drive, preferrably 20 GB or larger
CD-ROM drive for installation
For Mac OS X:
PowerPC G3 CPU 500 MHz or faster, including all PowerPC G4 CPUs. PowerPC G5 Power Macs with PCIX slots require the PCIX-424 card. PowerPC G5 Power Macs with PCIe slots and Intel-based Mac Pros are not compatible with the PCI-424 or PCIX-424 cards (requires PCIe-424 card).
128 MB RAM; 512 MB or more recommended
Mac OS X version 10.8, 10.7, 10.6, 10.5, 10.4, 10.3 or 10.2; v10.2.4 or later is required, and v10.2.8 or later is recommended.
Hard disk drive 20 GB or larger
Available PCI slot for PCI-424 or PCIX-424 card, or PCIX slot for PCIX-424 card
CD-ROM drive for installation
For Windows:
Pentium CPU (or equivalent) 800 MHz or faster; Pentium III CPU or faster recommended
128 MB RAM; 512 MB or more recommended
Windows 8, Windows 7, Vista, XP, 2000, ME, or 98; Windows 98SE or later required.
Hard disk drive, preferrably 20 GB or larger
Available PCI slot for PCI-424 or PCIX-424 card, or PCIX slot for PCIX-424 card
CD-ROM drive for installation
as far as i know the latest intel chipsets to support 5v pci were the 945 + 965 chipsets
there could be some AMD / GigaByte / Asus boards that will work with 5v pci beyond that, but not
according to gemini AI the p965 / ICH8r motherboards are the sweet spot
because of the native AHCI capability (in osx 10.7)
The Intel P965 chipset is the definitive "sweet spot" for running the original 5V MOTU PCI-424 card over later P35 and P45 motherboards due to how the physical PCI bus, signaling voltage, and Core 2 Duo/Quad architectures intersect.
The key technical reasons explain why this specific generation is required for a stable audio rig:
1. True Native 5V/3.3V Universal PCI Support (The ICH8 Southbridge)
P965 (ICH8): The P965 chipset utilizes the ICH8 southbridge, which features native, legacy PCI support built directly into the silicon. This native implementation properly routes and isolates the 5-volt signaling path required by the original, un-notched 5V PCI-424 card.
P35 (ICH9) & P45 (ICH10): As Intel moved to the ICH9 and ICH10 southbridges, they began phasing out legacy PCI logic to favor PCI Express (PCIe). To physically include standard PCI slots on P35 and P45 motherboards, manufacturers had to use third-party PCIe-to-PCI bridge chips (like ITE or Texas Instruments). These bridge chips strictly enforce modern 3.3V signaling, making them electronically incompatible or highly unstable with older 5V legacy audio hardware.
2. High-Performance Core 2 Duo / Quad Architecture
If the only goal was finding a 5V PCI slot, older chipsets like the Intel 865 or 945 would work. However, the P965 is the "sweet spot" because it bridges the gap between old power delivery and modern processing:
It is the first chipset generation fully optimized for the Core 2 Duo and Core 2 Quad (Conroe/Kentsfield) microarchitectures.
This allows you to run a highly capable multi-core DAW environment with plenty of CPU headroom for modern plugins, while safely running a 5V legacy audio card on the exact same board.
3. The Power Regulation Danger on P35/P45
Even if you find a P35 or P45 motherboard that physically allows you to seat the 5V PCI-424 card (using a universal slot layout), the power delivery on those boards is tailored entirely around 3.3V logic. Force-running a 5V high-draw card like the MOTU 424 on a bridged P35/P45 slot often triggers a combination of:
Excessive heat generation on the motherboard bridge chip.
Severe PCI bus dropouts, clock sync errors, and audio artifacts (pops/clicks) because the bridge chip cannot handle the legacy bursts of the MOTU architecture.
Risk of permanently frying the motherboard’s localized power regulators.
Summary
The P965 motherboard represents the absolute final engineering generation where Intel provided native, un-bridged, high-bandwidth 5V PCI support alongside high-performance multi-core CPU support. Going any newer (P35/P45) breaks the physical power and signaling compatibility, while going any older leaves your DAW severely starved of CPU power.
i dont agree with that last line!!! its not starved of cpu power.. lol its just not the best it can do... thats all. the pci-424 card will work great on any machine from a g3/g4 to a ich8r powered core 2 duo quad lga775 from 2006!