Originally Posted by Dopamin3
Yes it's the same concept in this scenario. Officially, AMD processors only support DDR2 1066mhz or DDR3 1333mhz when using two sticks. If populating 4 slots, DDR2 800mhz or DDR3 1066mhz is officially supported. Usually on AM3 the CPU-NB voltage can be increased and it may be possible to run 1333mhz, especially if it is the C3 stepping CPU with the improved memory controller. However, personally I had an x2 7750 (based on Phenom I architecture with 2 cores locked) and I couldn't get 4 sticks of 1066mhz stable no matter what I did. I had to back down to 800mhz.
DDR3-1333Mhz is supported on 4 DIMMs with C3 and E0 revision CPUs.
Of course, this is official rating, in actuality you can go much further than this. Might've been a weak multiplier holding you back at stock; I'm surprised you're actually able to run it well overclocked, most generic RAM (1333 CL9) tends to hold back overclocks quite a bit.