33MHz and 66MHz in 64-bit PCI?

[flipdon]

If you stick two 64-bit PCI cards (one that runs at 33MHz and one that can run up to 66MHz) in your mobo, assuming they have 64-bit PCI slots that support up to 66 MHz, the bus will be forced to run only at 33 MHz right?


if so.....time for a new gigabit ethernet card

 

[Agamar]

Well, it depends on the type of motherboard I think. I believe each slot is independent for the 33/66 bus.

 

[Scootin159]

<< Well, it depends on the type of motherboard I think. I believe each slot is independent for the 33/66 bus. >>



I'm not sure for 64-bit cards, but I know for 32-bit cards they are all forced to run at the slower speed (and I would assume that theory would translate over). Although it is possible for there to be 2 seperate PCI busses, in which case they could hit different speeds.

 

[flipdon]

<< Well, it depends on the type of motherboard I think. I believe each slot is independent for the 33/66 but. >>



wouldn't that mean that each slot has its own separate bus? hmmm... its all in reference to the new Tyan mobo with the MPX chipset. has there been any previews around on it?

 

[SCSIRAID]

If you put the two cards on a single PCI bus then the PCI bus will downshift to 33Mhz. This is done via a pin called M66EN which is grounded on a 33Mhz card. When the PCI bridge senses M66EN at ground it runs at 33Mhz. The real question is are the two slots on a single bus? The answer is probably yes but it depends on the MB. How many slots on the MB? How many are 32bit? 64bit? Whose core chipset? ServerWorks? Cant remember for 66Mhz std PCI but I believe you can get at least 2 slots on a single bus. PCI-X 100 can support 2 slots while PCI-X 133 can only support one.