Can I use a x4 PCIe card in XServe

Trying to install a Highpoint 2310 eSATA card in an Intel XServe. The computer can see the card and get manufacturing ID info, but I can't connect to the Web management interface or see any of the drives. Manual says x8 or x16 cards- the 2310 is x4. Is that the problem?

Thanks!

-dwc