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Using a PCIe x1 card in a PCIe x16 slot


Here is something I recently found out. I have tired this and it works.

You can use a PCIe x1 card, or a PCIe x4 card in a PCIe x16 slot. They work fine. So if you think you are short of PCI-e slots, you may not be. A shorter PCIe card works fine in a longer slot.

On PCIe X1, X4 and X16 slots, the first 18 pins are all wired the same, so as long as the PCI-Express card fits in the PCI-Express slot, it should work.

This is not the case for the legacy PCI (32-bit, non-express) slots, that are not PCI-Express. Those are not compatable with PCIe cards.


Picture of assorted PCIe and PCI slots.

The top four slots, in the picture above, are, from the top to bottom,
PCIe x4 slot , PCIe x16 slot, PCIe x1 slot and another PCIe x16 slot. A PCIe card that can physically fit in any of these slots will work, even if it doesn't fill the entire slot.

The bottom, 5th slot, is a PCI legacy (32-bit) slot. PCIe (express) cards will not work in this slot. It only accepts legacy PCI cards.


Here is the PCI-Express page on Wikipedia showing pinouts, etc.
PCI Express - Wikipedia, the free encyclopedia

YouTube Video showing PCIe X1 card in a PCIe X16 slot.
x1, x4 pci Cards Fit Into x16 pci-e Slot - YouTube

Here are links to discussions on this subject at Tom's Hardware.

"Can I install a PCI-e x1 Wireless network card in a PCI-e x16 slot?"






It's been like that since the beginning of PCIex !!!

Of course it has, but not everyone knows this, judging by so many comments on Toms Hardware and YouTube.

One thing you need to watch out for is that it may change the slot for your graphics card from an X16 slot to an X8 slot. Read your motherboard manual. Maybe your very expensive graphics card work just as great in an X8 slot, I don't know.

I was thinking more of a x1 or x4 in a larger slot. Those should work fine. Putting an x16 in an x8 may not work so well.

Here's a funny video on YouTube. A guy takes a Dremmel tool and makes an x16 video card into an x1 card by CUTTING OFF MOST OF THE SLOT CONNECTIONS. DON'T TRY THIS AT HOME.

Modifying a PCI-E 16x Card to fit into a PCI-E 1x slot
Modifying a PCI-E 16x Card to fit into a PCI-E 1x slot - YouTube

I was thinking more of a x1 or x4 in a larger slot. Those should work fine. Putting an x16 in an x8 may not work so well.
As soon as you put an x1 or x4 card into one of those larger slots, your bios may change the X16 slot to an X8 slot. Your graphics card may probably work just as great in an X8 slot.

As soon as you put an x1 or x4 card into one of those larger slots, your bios may change the X16 slot to an X8 slot. Your graphics card may probably work just as great in an X8 slot.
You are probably right, judging by the video above that makes an x16 video card work in an x1 slot. x8 video would probably be okay for most uses, but not for gaming or things that require intense graphics.

Only very powerful GPUs would notice the change from x16 to x8 slot. As mater of fact, only top of the line, gaming MBs can run all of multiple GPUs at x16 speed. Most of the time second GPU has to run at x8 speeds and some times even all at x4.
My Gigabyte ga-890fxa-UD5, for instance, can run one GPU at x16 and consequent ones share bandwidth of the rest of PCIx slots so next one would run at x8 and other 3 would run at x4 speeds while on almost same MB, ga-890fxa UD7, all slots would run at x16. That one was almost twice as expensive though.

I think the speed changes only if the card installed in the 16x slot is a graphics card. If it is something else, it could stay 16x. You can check that with some utilities such as Aida64

I think the speed changes only if the card installed in the 16x slot is a graphics card. If it is something else, it could stay 16x. You can check that with some utilities such as Aida64
It doesn't matter which kind of card is installed if slots share the bandwidth.

Using a PCIe x1 card in a PCIe x16 slot