Patch 2112 is required for Radical support. A newer patch just came out (patch 2486) which supersedes 2112. It has a few more bug fixes in.
You need at least Irix 6.4 with patch 1908 loaded. A newer patch just came out (patch 2505) which supersedes 1908. It has a few more bug fixes in. Both of these patches require patch 1887 to be loaded as well.
In Irix 6.5, there is no special software needed to access the Radical card. It is all included in the dmedia_eoe package that is installed by default.