[rotuts]

would someone explain the differences in the above bus(es). what cards go for the newer not yet available for G5?

could find this in a search

thanks rotut

[P]

PCI stands for Peripheral Component Interconnect. It's the old standard for external boards that ha sbeen around since the mid-nineties. Transfers at 33 MHz, 32 bits in most cases. There are different versions, at 5.0 V and 3.3 V, and also with a higher clockspeed or bus width. The highest clocked version is called PCI-X - 133 MHz and 64 bits DDR, I think. It's backwards compatible with older PCI boards (of the right voltage, 3.3 V).

PCI express, not extreme, (PCIe) is a completely different technology that happens to share the same name as a marketing trick.

Current G5s use PCI-X. Older Powermacs use PCI, of some speed. There are at this point no Macs that support PCIe.

[Calli46]

---- Quote from P ----
"...PCI express, not extreme, (PCIe) is a completely different technology that happens to share the same name as a marketing trick."

PCIe is a replacement (read faster) for AGP extension slot. New top-of-the-line graphics cards will be (are?) PCIe brand. Be aware too that PCIe cards are not AGP compatible (and vice-versa).

[Tyler McAdams]

PCI express is the new standard that is replacing PCI-X and pci. Most of the new video cards are coming out on the pc side of things as pci express boards... they are not backwards compatible with agp.

more than likely it will be a while before pci express hit the mac side of things.

PCI-X is still very dominant in workstations and servers. You can find most workstation boards on the pc side that are comparable with the G5 workstation board that have pci express slots for the video cards and still pci-x for the scsi adapter and nic card adapter slots. I have to this date only seen one scsi card that uses a pci express connect and have not seen any pc board yet that support it.

pci express comes in different connector sizes, the bigger the slot, the more through put it is capable of.

[P]

Originally posted by Calli46:
---- Quote from P ----
"...PCI express, not extreme, (PCIe) is a completely different technology that happens to share the same name as a marketing trick."

PCIe is a replacement (read faster) for AGP extension slot. New top-of-the-line graphics cards will be (are?) PCIe brand. Be aware too that PCIe cards are not AGP compatible (and vice-versa).

Well... It's a replacement for both. There are variants of the PCIe slot, like 1x and 8x and 16x, which refer to the number of channels the slot can use. The fastest, 16x, is often used for graphics. The spec actually allows for 32x, and you can bet that there are going to be even higher speed. AGP is itself a bolt-on onto PCI, sort of an extra backdoor connection to main memory for a regular PCI slot.

[jcadam]

There were thoughts of implementing an AGP 16x (twice the throughput of AGP 8x), until the industry decided to go with PCIe (good decision).

At the time Apple designed the PM G5, PCIe was still in the design process itself, so they went with PCI-X, thinking it to be at least some kind of "step-up". In reality, there are a scant number of cards for the PM G5 that utilize the extra speed of PCI-X. All that PCI-X gave us was broken compatibility with older PCI cards.

I expect Apple to implement PCIe in the next "major" mobo revision in the PM G5. They figure they have some time on their hands, as PCIe won't make much of a performance difference (in graphics) until the next generation of GPUs arrive. Not to mention that some form of regular PCI compatibility will need to be retained. Expect an increase in the total # of expansion slots (and a modified case design to accomodate)

Yes indeed, a VERY significant revision of the PM G5, which they are probably working on now.

[MORT A POTTY]

Apple would have to have ATI and/or nVIDIA prepare a PCIe card or two for launch.

I'd guess either the X850 from ATI and maybe and nVIDIA GeForce 6600 series card.


but in reality, Apple can take as long as they want with this because the AGP 8x bus isn't really being saturated yet at all, and the only reason to go PCIe right now is for SLI.

[P]

Originally posted by MORT A POTTY:
Apple would have to have ATI and/or nVIDIA prepare a PCIe card or two for launch.

I'd guess either the X850 from ATI and maybe and nVIDIA GeForce 6600 series card.


but in reality, Apple can take as long as they want with this because the AGP 8x bus isn't really being saturated yet at all, and the only reason to go PCIe right now is for SLI.

Well, if you want to use two video boards you don't have put one in a very slow PCI slot... Yes, the benefits from the consumer's standpoint are small, but a well-designed PCIe board is "cleaner" and should be cheaper to build. It's also a lower latency solution than PCI+AGP, which should help Apple since they insist on building machines with limited video memory.

For some reason, both nVidia and ATi seem to be embracing PCIe as fast as the possibly can, so there are lots of boards available. nVidia also claim OS X compability for the new boards:

http://www.nvidia.com/object/geforce6_techspecs.html

(Yes, they did that for the 5700 as well, and we never saw it. Too bad, a 5700 non-ultra in the iMac G5 might have been a good match)

The Radeon X300 and Radeon X600 are really a 9600 with a PCIe bridge chip, so the driver for those should be trivial. I'm also suspecting that the next iMac iteration will have a Geforce 6200, and that that is the entry-level board for the PowerMac as well.

[goMac]

Originally posted by Calli46:
---- Quote from P ----
"...PCI express, not extreme, (PCIe) is a completely different technology that happens to share the same name as a marketing trick."

PCIe is a replacement (read faster) for AGP extension slot. New top-of-the-line graphics cards will be (are?) PCIe brand. Be aware too that PCIe cards are not AGP compatible (and vice-versa).

Are would be correct. My mid-range PC has a X700 PCI Express.