I think the L3 adds it s latency to the pocesing chain.The RAM latency is already there and the L3 adds even more.
Most probable the RAM or a part of it is used/reserved as L3 cache ,when there isn t one on the die for a multicore CPU liek the Athlons.
Looking at the toms hardware we see that in multithreaded apps the Athlon 2 does better than the Phenom 2 .
What about FM2 motherboards with 2 APU sockets and GDDR5 on-board AMD ?! Maybe i am to sarcastic sometimes