Using the 4 lane PCIe card in a 16 lane slot with the

[Gary Taylor]

Sorry I left Multibridge Studio off the end.

[Matt Dowling]

Hi Gary,

No, this will not work – you can put a x4 in a x8 slot though.

Many boards are now coming out with PCIE x4 slots and PCIE x16.

Cheers,

Regards,

Matt
Blackmagic Design

[Gary Taylor]

Hi Matt,
Thanks for the answer Matt. I would be great if you guys had an x16 card also. With the proliferation of SLI motherboards there are going to be many with two x16 slots and it would be great to use the Multibridge with them.
Thanks again!
Gary

[Michael Grossmann]

Hi Gary,

IMHO, I think that you should be able to use a x4 card in a x16 slot, even if it’s only routed with x4 lanes.

I found a specification file for PCIe slot on the website of PCI-SIG, whose who are responsible for the PCIe standard,
which explains how PCIe works and which card can be used in which slot.

https://www.pcisig.com/specifications/pciexpress/technical_library/dev_con_09_02/specifications/pciexpress/PCIExpress_Cards.pdf

Important are the pages 11 and 17.
On page 17 you can see an explanation:
The point “Down-shifting” says that for example a x16 card only works in a x16 slot which is fully routed.
The only exception of this rule is the x8 slot. A x8 card also works in a x8 connector which only have x4 lanes routed.
Your problem using a x4 card in a larger slot which have x4 lanes is not a problem of “down-shifting” because you only need x4 lanes.

[Matt Dowling]

Hi Michael,

I stand corrected! You are correct, my mistake. You can put a 4x in a 16x slot.

Cheers,

Regards,

Matt
Blackmagic Design

[Gary Taylor]

Thanks Michael and Matt, that is great news!!! Dual Opteron here I come!

[Michael Grossmann]

Hi Gary,

I’d like to know which mainboard you want to use. I have the Tyan K8WE with two full x16 PCIe slots but with a Decklink HD PCI-X card.

Thanks in advance,
Michael

[Gary Taylor]

Hi Michael,
I am planning to get the same motherboard although I just heard something interesting about IWill Motherboards. Unless I something else happens to get me excited about another board I am planning to stick with the S2895. I like the guys at Tyan and they answer the phone which has it’s advantages when you are in a pinch.

That board has great features including the onboard SCSI option with the S2895UA2NRF MB. If I remember correctly you didn’t get that board did you? I was hoping you might be able to report on the perfomance of the onboard SCSI RAID. Did you try the onboard SATA RAID? I am pretty excited about this new system. Can’t wait to see that the dual core 275 chips will do.
Hope that helps,
Gary