With the info from Ratata I got them to work more or less. Very slow though. Looks like they need strong input from the antenna. I also have two card from Skydvb in the same tv-server which respond much better. And they also have support for CI+!
I´m using Boxer as provider.
I have a server with 3 cards. One 6590 an two DVBSky T980C. The two cards are set up with CI+ and work quite well I think.
The 6590 is rather slow in shifting channels I think and I don´t get as many channels as with the T980C.
I also use a card splitter so I can have coded channels for all 4 receivers.
The web says that you can´t get CI+ with the T980 but it works for me. No problem to look at HD channels.