Can I plug a PCI-E DAQ card into a PCI-E x16 slot

[aml1138@yahoo.com]

I have a small form factor PC that only has a PCI-E x16 slot.  Can I plug in the PCI-e DAQ into it?

[samantham]

Hello,

Yes, you should be able to use the PCIe DAQ in a x16 slot, however there is a small except that pertains to x16 slots being reserved for graphics card expansion. 

For example, I looked up the specification manual for the PCIe 6251.  This device is x1 form factor and is compatible with x16 … plus a note about the graphics exception.  A section of the spec. manual is below.

PCIe devices

Form factor .................................x1 PCI Express,

specification v1.0a compliant

Slot compatibility........................x1, x4, x8, and x16

PCI Express slots (note:2)

Note 2: Some motherboards reserve the x16 slot for graphics use. For PCI Express guidelines, refer to www.ni.com/pciexpress.

The web reference pertains to this section of subtopic titled Physical Layer in the document linked below. 

“Using a smaller-width expansion board in a larger-width connector – is up-plugging. Up-plugging is allowed, but with the caveat that the motherboard vendor is required to support the expansion board at only a x1 data rate while in this configuration, potentially wasting the investment in the expansion board with the faster interface. Whether a particular motherboard can handle an expansion board at its full data rate in an up-plugged configuration must be confirmed on a case-by-case basis with the motherboard manufacturer. For example, some motherboards can handle a x4 expansion board at its full x4 data rate when plugged into a x8 or x16 slot while other motherboards from the same vendor might run the board only at x1. In the case where a motherboard has both an integrated (onboard) graphic controller and an x16 PCI Express slot for future graphics expansion, it is normally not possible to use that x16 slot at the same time as onboard graphics are enabled.”

PCI Express – An Overview of the PCI Express Standard

In summary, the graphics card exception is motherboard dependant.    What PCIe DAQ board do you have?

[aml1138@yahoo.com]

Thanks.  We're thinking of using the 6259 PCi-e.

[jonatmudd]

I'd be curious to hear how using 6259's in a x4, x8 or x16 slot panned out for you?  I just bought two 6259's and am not hunting for a computer to accommodate them. Seems x1 expansion slots are quite rare...at least Dell seems to have mostly x8 and x16.

Also, I am a little confused by the example in the documentation.  It says an up-plugged x4 may run at x4, orr at x1.  Seems to me that , if you are up-plugged, it is always possible to run at a lower rate, but never a higher one.  If this is true, doesn't that imply you can plug an x1 card into an x16 slot, and be guaranteed it will run at x1?  This seems to be a logical conclusion because an x1 card can never run higher than x1; and in this case it can't run at anything less, since there isn't any lower it can go. Or am I really missing the boat (happens all the time... 😃 )

 Thanks-

[HeatherBaker]

Hi jonatmudd,

I believe the excerpt you are referring to is copied below.  Unfortunately, it is all dependent on the motherboard of your computer and you should contact the manufacturer.  Since you mentioned Dell, then you may find their PCI Express document of use.

"Up-plugging is allowed with the caveat that the motherboard vendor is required to support the expansion board at only a x1 data rate while in this configuration, potentially wasting the investment in the expansion board with the faster interface. Whether a particular motherboard can handle an expansion board at its full data rate in an up-plugged configuration must be confirmed on a case-by-case basis with the motherboard manufacturer. For example, some motherboards can handle a x4 expansion board at its full x4 data rate when plugged into a x8 or x16 slot, while other motherboards from the same vendor might run the board only at x1."

[jonatmudd]

Thanks.  There's another document I was guided to that was very helpful. It says that an x1 card, *must* be supported with any width slot, x1, x4, x8, or x16.

The document (whose link I don't seem to be allowed to post...who knows why) is document ID 4037.

It has a table that basically shows x1 must be supported by all slot widths

However, the same can not be said of any other width card.