You need to figure out on your board which slots will provide 16/16 or 8/8 lanes for dual cards depending on platform and CPU (lanes available). You might have the right bridge. Alternatively, if your board is SLI capable it would have come with a bridge in the box. You need to match spacing with that bridge for proper slot usage. Nvidia and eVGA both have slot numbering on their sites so you purchase the correct HB bridge.
Also, depending on how new the board is, the bridge that came in the box might be a HB already.