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I have a will a PCI Universal card but not slot. Will it work in a PCI-E X16 slot?

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No it won't. They Are two different standards – Ramhound Aug 22 '13 at 10:26

Typical PCI cards have either one or two key notches, depending on their signaling voltage. Cards requiring 3.3 volts have a notch 56.21 mm from the card backplate; those requiring 5 volts have a notch 104.47 mm from the backplate. "Universal cards" accepting either voltage have both key notches. This allows cards to be fitted only into slots with a voltage they support.

enter image description here

PCIe devices communicate via a logical connection called an interconnect or link. A link is a point-to-point communication channel between two PCIe ports, allowing both to send/receive ordinary PCI-requests (configuration read/write, I/O read/write, memory read/write) and interrupts (INTx, MSI, MSI-X). At the physical level, a link is composed of 1 or more lanes

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Various PCI slots. From top to bottom:

  • PCI Express x4
  • PCI Express ×16
  • PCI Express ×1
  • PCI Express ×16
  • Legacy PCI (32-bit)

PCI Express - Source Legacy PCI - Source

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Possibly ...

They do make pci to pcie adapters and I think you can put them in an x16 slot.

enter image description here

You'd have to get creative with some case modding but if it's a full height pci card you'd need something like this:

enter image description here

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The top picture is a card designed to fit a half-height PCI card into a PcE slot. The bottom one is typically used with a small formfactor motherboard in a big case so there is space next to the motherboard for the extra PCI slot. (And the case has a corresponsding slot for the slot-plate of the PCI card.) The mounting holes should match up with the spacers on the backplate of the case where a full-size motherboard would have an extra row of holes. – Tonny Aug 22 '13 at 18:39

Totally different and incompatible standards.

It won't even physically fit.

So the answer is: NO.

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You are confusing PCIe with PCI-X. PCI-X slots were 64-bit (as opposed to regular PCI slots, which were only 32-bit), and came in a 3.3V and 5V variety. They were keyed differently so that a 5V card could not be plugged into a 3.3V slot or vice versa. A "Universal" PCI card simply means that the card can be inserted into any type of PCI or PCI-X slot.

PCI-X slots were only ever found in servers. They (like PCI) disappeared once PCIe took over. Neither standard is compatible with PCIe, nor will they fit into a PCIe slot.

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Regular PCI slots came in both 32 bit and 64 bit versions. The 64 bit versions were rare in the PC consumer world, but I have used them on workstation class boards as well as in servers and in ancient Mac G3's. Which makes the "which were only 32-bit" part not fully true. Ditto PCI-X (once again, mostly servers and prosumer class devices, not bargain bin class PCs). – Hennes Sep 13 '14 at 10:14

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