It is like "updatelee" said that it depend on the server, maybe it can only inserted by lie down our card. if you can inserted like this,maybe you can use it .
We use them in 1RU servers, but there is a little mechanical problem - lower F-connector is situated too low and you will have to saw off couple of millimeters from your server enclosure.
One more thing - on some servers (mainly HP) you should switch PCIe to x1 mode and ensure, that proper voltage is supplied, either from PCEe settings, or by connecting ATX power directly to TBS card.