That is for the "adapter" version of the PERC.  The adapter and the "integrated" versions run slightly different firmware.  If you are running 6.3.1.0003, then you are at the latest for the PERC 6 in a 1950 (integrated version).
I'm currently running: 6.3.1-0003 and I downloaded this SAS-RAID_Firmware_3P52K_WN32_6.3.3-0002_X00.EXE found here:  [URL]# However it simply reports "This update package is not compatible with your system configuration" I also look at the support page for the server and it only lists 6.3.1 as compatible so anyone have any idea what's going on? Thanks in advance.    
PowerEdge 1950 Windows 2008R2 OpenManage 7.3 reports Perc 6/i reports Latest 
Available Firmware Version 6.3.3-0002