Intel X520 DA2 Fiber Optic Card 2-port 10Gb PCIe v2.0 (5.0GT/s) x8 cards are not designed to be put into desktop X16 Video Slots nor are they a Dell Product or supported by Dell in Desktops.

Cisco SFP-10G-SR

The Cisco 10GBASE-SR Module supports a link length of 26m on standard Fiber Distributed Data Interface (FDDI)-grade multimode fiber (MMF). Using 2000MHz*km MMF OM3

http://www.intel.com/support/network/adapter/pro100/sb/CS-030612.htm

 

http://ark.intel.com/products/39776/Intel-Ethernet-Server-Adapter-X520-DA2

What are the SFP+ direct attach cable requirements for the Intel® Ethernet Converged Network Adapter X520 Series?

• Any SFP+ passive or active limiting direct attach copper cable that complies with the SFF-8431 v4.1 and SFF-8472 v10.4 specifications.
• SFF-8472 Identifier must have value 03h (SFP or SFP Plus). You can verify the value with the cable manufacturer.
• Maximum cable length for passive cables is 7 meters

 

 

That's true, But they are supplied by you.  And the Dell website even goes so far as to say these NIC's are compatible with a Lattiude E6400... Yup a Laptop, see here. 

So getting around the fact it's Intel, and Dell say this PCIe card works in a laptop which it can't physically fit into.  this card works fine in this rig. What I want to know it the compatibility issues that stops the SFP SR that comes with this card from working with a Cisco SFP+ LRM.  Both SFP's are 10G and both are MM.

Or have I just wasted £1500 of taxpayers money by buying something to run 10G SFP's that aren't compatible with other 10G SFP's?