vashim66 said:
First of all, no you cannot upgrade a PCI slot to PCI-X.
Secondly, the powermacs do not use the PCI-X slots for their graphics cards, they use an AGP slot. AGP slots are currently being phased out for PCI Express (PCIe for shot) not PCI-X, which is entirely different.
All depends on the motherboard you have, the Rev. A PowerMac G5s used the same motherboard as the PCI-X PowerMacs -- which means they do have a PCI-X HT Tunnel, it's just crippled to run at PCI speed.
Could be a resistor setting or a firmware setting, don't know.
But it's rather like the PowerBooks vs. iBooks and the Pro-machine having spanning and the consumer doesn't even though it's the same chipset, and sometimes even the same graphics chip.
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The Rev. B machines don't use the same motherboard -- they don't have a PCI-X HT Tunnel and use the PCI bus on the KeyLargo 2 chip.
The SP Rev. B machine uses the iMac G5 board -- so likewise no way there.
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On the Rev A machine you'll need to find out who made the PCI-X HT Tunnel and how to convert it from PCI to PCI-X speed, if it's an AMD-8131 chip...
There is no physical difference in the slot, the SP PM 1.6 even has a PCI-X HT Tunnel, it just operates at PCI speed locking out the 100/133MHz PCI-X speeds.
The on-line .pdf for the AMD-8131 has a chapter on how to configure the PCI-X HT Tunnel...
sample bridge chip docs said:
If the systemboard supports PCI-X mode operation for a bridge, then a pullup resistor to VDD33 must be placed on the bridges PCIXCAP pin. To limit the frequency of a PCI-X-capable bridge to 66 MHz on a systemboard, the systemboard must also include a pulldown resistor from the bridges PCIXCAP pin to ground. The strapping options on GNT[4:3]# are used to distinguish between systems that support 100MHz and 133 MHz; in either of these two cases, the system board should include no pulldown resistors on PCIXCAP.
