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Can PCI-e 16x slots be used for PCI-e 1x cards?

Last response: in Graphics & Displays
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June 22, 2007 8:53:22 PM

Hello people;

I think that I have an interesting question which could "puzzle" most of us:

I am about to buy a new motherboard,
and I'm in for a big dillemma:
I am not a real gamer,
so I am not (immediately) interested in putting 2 video cards in my pc (SLI or Crossfire).

BUT, as you know, the best motherboards out there are all SLI- or crossfire motherboards with TWO PCI-e 16x slots. :!:
The problem is that those mobos always have 1 PCI or PCI-e 1x slot LESS than mobos which have only 1 PCI-e 16x slot.

So I was wondering:
If I take a mobo with 2 PCI-e 16x slots, and I use only 1 video card,
could I use the other PCI-e 16x slot for a PCI-e 1x interface card?
For instance, a PCI-e 1x TV-tuner card or so.

:idea: I read somewhere that PCI-e 8x slots can be used for PCI-e 4x or even 1x cards, so I'm wondering if the same downward-compatibility goes for PCI-e 16x slots.

In short, I am well willing to pay extra for a good mobo, with a well made BIOS, a perfect board-layout and so forth,
but then I almost have to get a higher-end mobo with dual PCI-e 16x.
Does that mean that I will end up with 1 useless PCI-e 16x slot,
or can I use that slot for cards which use a PCI-e 1x or 4x interface?

Thanks a lot in advance for your help!
Carl
June 23, 2007 2:28:06 PM

Does this mean that no one has a clue? :-)
June 23, 2007 2:39:44 PM

I think you can. Tom's have 2 articles where they taped the connectors on some gfx card to limit bus interface. That worked fine, so I 'm guessing yes.
Related resources
June 23, 2007 2:58:01 PM

If the PCIe x16 slot complies with the regulations set for PCIe and the device does too, it will work.
As always some manufacturers work sloppy and i´ve read about some boards that which PCIe slots can´t scale up or down - or don´t even work properly at all. I´d be cautious if your board has a via chipset (it probably doesn since it features 2x PCIe 16x, but you never know...).
June 23, 2007 3:00:16 PM

From the Googling I did, it appears you can always install a lower lane card (x1 in this case) into a higher lane slot (x16).
June 23, 2007 3:20:01 PM

i just hope you realize that there are plenty of great boards with such features that do not have 2 16x pci express slots. and to answer your question yes as pci express scales.
June 23, 2007 3:50:52 PM

Here is a very good motherboard with 1 16x and 3 1x slots. Look around because no matter what your perticular needs are I'm sure you can find a board to fit them.
June 23, 2007 4:30:23 PM

Quote:
From the Googling I did, it appears you can always install a lower lane card (x1 in this case) into a higher lane slot (x16).


This was my understanding of PCI-e x16, it can scale down to x1.
June 23, 2007 7:58:02 PM

And what about SLI and Crossfire?
If you only use 1 video card,
are you still limited to NVidia for SLI and to ATI for crossfire?
Or does this limitation only count if you actually use 2 video cards?

So I mean, can you:
- install 1 ATI video card on an SLI mobo, and
- install 1 NVidia video card on a Crossfire board?

Thanks tou you all for your help.
Carl
June 23, 2007 8:02:53 PM

Quote:

So I mean, can you:
- install 1 ATI video card on an SLI mobo, and
- install 1 NVidia video card on a Crossfire board?

Thanks tou you all for your help.
Carl


Yes to both your questions
!