Concerning the PCI-X slots in the new G5s. Are they backward compatible with older PCI cards such as a SCSI card. I have an old Arcus II Warhorse that I'd hate to have to give up, if I take the plunge.
I don't it's a dumb question. You never know when new stuff comes out. Looks like it will work. Here is some info I found.
Some FAQ's about PCI-X (from Compaq's web site)
Will new PCI-X cards be compatible in conventional PCI based systems?
Yes, PCI-X cards can be used in a conventional PCI system. PCI-X is backwards compatible with conventional PCI products, which allows existing PCI-X cards to operate within a PCI environment. However, the PCI-X card will default to the speed of the PCI bus (either 33 MHz or 66 MHz).
Will PCI-X systems allow the use of conventional PCI and PCI-X cards within the same server?
Yes, PCI-X systems will allow the use of both PCI and PCI-X cards on the same bus, however the bus speed will default to the speed of the slowest card. For instance, if you placed a 66 MHz card in the same environment as a 133 MHz card, the bus speed would operate at 66 MHz.
Will conventional PCI cards be compatible in PCI-X based systems?
Yes, conventional PCI cards will be compatible in PCI-X systems. The PCI card will run at its assigned speed (either 33 MHz or 66 MHz), and will experience no speed improvements due to operating in a PCI-X environment.
133MHz PCI-X Expansion
The Power Mac G5 introduces Macintosh users to PCI-X. This advanced expansion protocol
addresses the need for higher-performance PCI devices, increasing the speed from
33MHz to 133MHz and throughput from 266 MBps to 2 GBps. PCI-X also operates more
efficiently than PCI, resulting in more usable bandwidth at any clock frequency—ideal for
high-bandwidth applications. The PCI-X specification uses 3.3V signaling and is designed
for compatibility with legacy 3.3V and Universal cards.