Testing a 64 bit processor on a 32 bit platform isn't really unfair.
It's like racing a rally car and a formula one car on muddy hills. Its obvious the rally car will win, but whats not obvious is how it will perform given the right environment.
EDIT: I also don't know what they were doing in those tests, but I can easily get 5500-5900 mB/s peak memory bandwith. Looks to me like they haven't configured that FX beast properly.
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