The thread is a bit old. But to sandbox242 and all others I can confirm that the Narra3 does support atleast the quad core Phenom II x4 945. Heard rumors about others(955 etc), but this 945 atleast runs good in my machine and others, and are up at the best you can get in the board. My board is running bios 5.17, but iv heard also 5.13 works. Bios wil not identify the CPU other than "unknown" but windows wil be able to use it fully and identify it correct.
IMPORTANT that you get the 95W version of any CPU, NOT the 125W versions... Mine is the HDX945WFK4DGI
As to my knowledge the Narra3 can not be unlocked in bios, so no new features or options like overclocking is possible.
Compared to the 9600 the 945 is alot better:
http://cpuboss.com/cpus/AMD-Phenom-X4-9600-vs-AMD-Phenom-II-X4-945-95W
CPU mark rating:
Phenom X4 9600: 2321
Phenom II x4 945: 3729