Intel 975x Chipset Mainboard compatibility with PCIe-PXIe Interface

[zeih]

Is the INTEL 975X Chipset compatible to the MXI-Express x4 card?

We are setting up a PXIe-system and want to make sure that we have full x4 PCI Express speed available.

In the MXI manual there is a paragraph stating that 'a host PC with an available x4 (or wider) PCI Express slot' is needed, but also that 'using a PCI Express slot wider than x4 may result in negotiation down to x1 width'.

The boards listet in the compatibility and recommendation list only have x16 PCIe slots for graphics cards and x1 PCIe slots for add-on cards. As we need the x16 PCIe for a graphics card, there is no x4 (or wider) slot to be used for the MXI card.

The INTEL D975XBX2 board has (as the only board we could find) one x16, x8 and x4 slot each and would therefore be our choice for the system.

Are there any experiences with that board, i.e. incompatibility issues or speed problems etc.? Has it been used successfully with a MXI-Express card?

A feedback would be greatly appreciated - many thanks in advance.

[ChristophS]

Hi,

unfortunately we have no information about compatibility of this Mainboard, I also asked in the USA , but they answered in the following way.
'Unfortunately, the motherboard list we've tested does not include the INTEL D975XBX2, and so I don't have any information on whether it works or not. I also checked the computers listed, and none of them use that chipset (as you mentioned already in your email). I know this isn't much of an answer but that's really all the information I have'

best regards.

Christoph Strasser | NIG AE

[zeih]

Thank you for the information and the effort to find out.

As this board and chipset has not been tested, do you have a suggestion for the system we need?

Again, we do want x4 PCIe speed and need one x16 slot for graphics.

Of the tested boards and systems (on the NI pages), many only have two x16 slots for SLI purposes that go down to two x8 slots when both are used - but none of them has a dedicated x4 slot... Unfortunately no information is given whether (when using the listed boards) the full x4 speed has been gained or whether a negotiation down to x1 has taken place.

Is there detailed information available on the tested systems, or can you suggest a certain board that fulfills our needs?

Thanks a lot for the effort.

[ChristophS]

Hello, I asked our USA colleagues and I got this answer:
'

So just a note on the reason why plugging a x4 board into a x16 slot *may* result in the device possibly operating at x1 speeds. The devzone article here has some good information, but I've quoted the relevant part below:

"It is important when choosing a computer to make sure that the PCI Express connectors are wired to the physical connection size. For instance, some vendors use motherboards with x8 connectors that are wired as x4. Devices in these slots will only operate at x4 data rates. In the case that you are up-plugging a PCI Express device, make sure that the computer you are using supports up-plugging at the maximum data rate supported by your device. The PCI Express specification only requires up-plugging to operate at the x1 data rate. This could result in a x4 device that is plugged into a x8 connector to operate at x1 data rates (250 MB/s)."
 
So, the speed really depends on the physical implementation of the particular slot. I'd suggest the customer find out from the computer/motherboard vendor how their slots support "up-plugging" as mentioned in the article, and this should aid with their decision.  I hope this helps, and let me know if you have further questions. Thanks
'
I hope it will help you.

Best regards
Christoph Strasser|NIG AE