Is it possible to put a PCI-X card in a PCI slot?

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By this, I mean is it possible to put a PCI-X card in a PCI slot? I heard from someone (who deals with servers all the time) that this is the case, however I may have misheard. Also, the card DOES fit, I'm wondering if they're electrically compatible.

Eli

Posted 2011-08-12T20:01:29.327

Reputation: 802

Answers

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Yes, as long as the PCI slot is a 2.x or later, PCI 1.0 was 5v while PCI 2.x was 3.3v - which is electrically compatible with PCI-X.

Source: Wikipedia PCI-X

Dustin G.

Posted 2011-08-12T20:01:29.327

Reputation: 2 025

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Maybe this new question adds some interesting detail to the things? http://superuser.com/questions/839893/i-have-a-3-3volt-pci-ethernet-card-working-on-a-5volt-pci-slot-how-is-it-possib

– Sopalajo de Arrierez – 2014-11-14T02:59:17.767

This answer is wrong, PCI 2.0 added the 3.3V option but it didn't remove the 5V option. The 5V option wasn't removed until 3.0 and even then there is nothing forcing motherboard manufactureres to use the latest version of the spec. – plugwash – 2017-06-07T14:31:15.980

Thank you! This helps a lot. Since PCI 2.0 was released in 1993, this pretty much means any PCI slot. – Eli – 2011-08-12T20:15:22.923

Just for future reference, the card in question was a Broadcom BCM5701, and it works in a normal pci slot as well as pci-x – Eli – 2011-08-13T00:23:24.903

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It all comes down to voltage.

PCI-X slots are always 3.3V.

In principle PCI slots can be either 3.3V or 5V depending on which version of the PCI standard they are designed to but in practice 3.3V ones are extremely rare.

Cards can be either 3.3V only, 5V only or universal voltage. Cards and slots are keyed to indicate the voltage.

So if your PCI-x card is keyed for universal voltage then it should work in a regular 5V PCI slot. If it doesn't support 5V then it shouldn't fit in a regular 5V PCI slot. If it fits but doesn't work then someone is failing to follow the specs.

plugwash

Posted 2011-08-12T20:01:29.327

Reputation: 4 587

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That isn't backwards compatibility. Putting a PCI card in a PCI-X port would be considered backwards compatibility - which is the case, as long as it is PCI 2 as the voltage on PCI 1 is not the same. To sum it up, PCI 2 cards can be put in PCI-X ports, not the other way around.

MaQleod

Posted 2011-08-12T20:01:29.327

Reputation: 12 560

1There are some PCI-X cards that are keyed in the same fashion as a PCI card and will work in a PCI 2.0 slot. The original question stated that the card does fit in the slot. – Dustin G. – 2011-08-12T20:25:04.990

PCI-X can go in to PCI slots by design. – Keltari – 2011-08-15T05:18:44.563

I have fixed the question title. – kinokijuf – 2012-02-29T17:44:26.990