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PCI-X question

W

windraider

Member
not sure if this should have been troubleshooting or GH, so i'll just put it here.
i'm assisting on a migration upgrade from some older equipment for a company, and they want to keep some of their legacy PCI cards and put them into new mobo's, unfortuantley the only real choices we have to upgrade to for mobo's are ones that have mostly PCI-X slots with one legacy PCI slot (don't ask, long story.) From the whitepapers and the PCI-SIG it says that PCI-X and PCI are backwards compatible, but the cards they have are not keyed correctly to fit into the PCI-X slots. is there an adaptor that will let a PCI card fit into a PCI-X slot? or am I just totally misreading things, or just missing something basic that should be obvious to me? thanks,

Cheers
 
It totaly depends on what their old cards are and also if you put a normal 33mhz 32bit PCI card into a PCI X slot it slows the whole PCIX bus that slot / card is in down the normal PCI speeds, so unless the motherboards you are getting have more than one PCIX bus you don't want to be doing this. and also even 64bit PCI cards should fit in PCI X slots it just uses the first part of the slot and not the back portion.
 
As i understand it there are 5v (old) and 3.3v (newer) versions of regular pci. Most newer motherboards are keyed to accept either one, BUT PCI-X slots are mostly ONLY backwards compatible with 3.3v pci cards

now i think i saw something somewhere about pci-x 2.0 that was supposed to guarantee full backwards compatibility, but that just might be a figment of my imagination.
 
PCI-X cards are backwards compatible, the slots are not "forward compatible" with older pre-PCI 2.1 cards, or many PCI 2.1 cards either. As stated above, older 33MHz PCI is 5V, while newer 66MHz+ slots are 3.3V and keyed so that older 5V cards won't fit in them. I've never seen adapters, but that doesn't mean they don't exist. What kind of legacy PCI devices are they trying to migrate? Would seem that most modern motherboards have moved everything onboard eliminating the need for most "legacy" 32-bit PCI devices in the server market, thus the elimination of them on many boards now.
 
it's not really for servers, more for workstations, they have a lot of older ones with proprietary programs for what they do and they're trying to migrate some older 4 & 8 port serial cards and some older video capture cards.
so basically from what's been said, if it's a 3.3v PCI card it should be keyed to fit and work in a PCI-X slot, and if it's a 5v PCI card it won't be keyed properly to fit into a PCI-X slot?
Thanks all

Cheers
 
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