I really appreciate you guys weighing in with opinions. I too, am worried that these risers are specific for the PCIe slots in those specific Supermicro motherboards. I see they have a heatsink sittiing on a PCIe to PCI bridge which makes me wonder if this might just generally work. It stands to reason, one would need the specific driver for that PCIe to PCI-X bridge. As far as I know, one can put a PCIe X8 connector in a PCIe X16 slot and it should work fine, right?
I will send supermicro an E-mail about this and maybe they will respond.
Ah Ha that extra connector is the "SEPC (Supermicro extended Power Connector) slot for 2U active riser cards w/ a power extension (i.e. CSE-RR2UE-AX)"
as stated here... http://www.supermicro.com/Aplus/motherboard/Opteron2000/MCP55/H8DM8-2.cfm
So, I guess without that SEPC slot, this card cannot run the PCIe to PCI-X bridge...