I ve played a lot with Athlon 6400+ and Phenom 2 memory timings and never achieved to much performance without secondary effects in stability or data corruption.
The only timing that will bring more performance is the Command Rate tweak , but if the memory or the memory controller doest want it at 1T you will have to Clear CMOS.
Having in mind the amount of memory modules you will NOT be able to tweak that one too.
The memory banks are full in your case ,you are using all slots ,so no memory tweak is possible due to the memory controller limitations.
I would be surprised to see your memory amount pass Memtest as it is at 1333 Mhz.
As you can see the motherboard already down clocked the RAM to keep stability.Maybe try the 1066Mhz(533Mhz)
Set Memory Clock from auto to manualNevermind you are already at 1066Mhz.
from what the bios picture shows.