Since that's your first post - welcome to Hexus! (ex-pat Bullwell/Bramcote lad misel')
30-40fps - surely that's "reasonable"? Remember this is a beta and I'm pretty sure that the US$8m will have been for joint promotion and perhaps some major tweaks for the current gen and Hawaii gfx cards. The ole Phenom II isn't the best engine for games these days.
24GB of memory - ouch! I've seen servers doing Oracle production that have less memory than that. Be a kick-ass virtual machine host though.
Just a thought - have you tried upclock on that processor? I'm running reasonably stable at 3.6 and 3.7 and there's been lots of talk that 4.0 is achievable with good cooling. There's a lot of discussions out there, like this one on boosting the PhenomII's speed. That said, I'm planning to jump to Haswell for my next build (or rather ... rebuild) since it's obvious that current games can't really make use of the six cores and Intel's less-but-faster approach is more suitable.
Got my BF4 Beta invite last night Unfortunately I won't be able to take advantage until the weekend because there's too much on.