I need to identify what kind of slots are available from my computer based on the shape of the slot. So far, I can easily tell the difference between 32-bit PCI and PCIe slots but I am having problem with 64-bit PCI and PCI-X slots.

From my googling, the slot itself looks like either a 3.3V 64-bit slot or a 3.3V PCI-X slot, but I cannot find any article that put both kind of slots together side-by-side for comparison. Is there any way to identify the slot based on the physical shape of the slot only?


From Wikipedia :

The 64-bit PCI connector can be distinguished from 32-bit by being longer, and from PCI-X by having three segments, with the one in the middle much shorter than the others. PCI-X slots can be distinguished from 64-bit PCI as the small segment is first, instead of in the center.

Comparison of slots

  • 3.3V 64-bit PCI slot has the small segment first as well. – Hery Feb 1 '12 at 2:27
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    Universal 64-bit PCI == PCI-X, then? – Kyle Smith Feb 1 '12 at 2:40
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    @Hery: there shouldn't be any significant physical differences between the slots. The newer PCI cards - 3.3V will fit (and work) in a PCI-X slot, and PCI-X cards will fit in an older PCI slot (as long as the voltage - 3.3V - matches). The standards are backwards compatible with the slowest connected card determining the bus speed. Perhaps you will have better success looking at the chipset or model of the motherboard. – cyberx86 Feb 1 '12 at 2:54
  • so physically there is no difference at all... For completeness' sake, what about 5V 64-bit PCI and 5V 64-bit PCI-X slot? Are they the same physically as well? – Hery Feb 1 '12 at 9:42
  • @cyberx86, maybe this new question adds a curious detail about what could happen in extreme PCI voltage compatibility cases? superuser.com/questions/839893/… – Sopalajo de Arrierez Nov 14 '14 at 3:01

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