Hi Phil,
South is correct when he says that the Intel adapters do not require any specific brand of direct attach cable. However, the Intel adapters do check to make sure that the attached cable identifies itself as either a passive SFP+ or an active SFP+ cable as specified in SFF-8472 Specification for Diagnostic Monitoring Interface for Optical Transceivers. For many SFP+ cables, this identification is present as expected and the cable works fine.
You can see the specification at ftp://ftp.seagate.com/sff/SFF-8432.PDF.
I have run into previous instances where some cables (including some HP cables) sometimes do not provide the identification the Intel device is expecting. My understanding is that cable vendors can supply you with an HP cable that does identify itself as an SFP+ cable and will work with Intel(R) Ethernet adapters. Because your switch requires an HP cable, you will need to get an HP cable that identifies itself as an SFP+ cable. You will not be able to use the Intel cable or any other vendor's cable.
Technical Details
Intel Ethernet adapters require the SFP+/ SFP identification bit (Address A0h, value of 03h) from the SFF 8472 identifier table. Intel Ethernet adapters accept active and passive cables identifying as 8,3 and 8,2 from the transceiver codes table.
Mark H