i do think that clock speed does matter but only until 3.4 ghz, after that having more cores are better then more clock speed. since i have only a phenom II 945 @ 3.0 ghz, i got a really good cpu heatsink and fan, and properly overclocked to 3.5ghz with no voltage increase, and running BF3 it only gets to 45 degress celsius and idle 26 degrees. matt is right though you should be ok, if you had only 3 cores at that clock speed i would worry. here is a good link Battlefield 3 Benchmark - BenchmarK3D
downoad core temp, and let that watch your cpu temps while playing bf3, you dont want your cpu getting over 60 deg celsius which my phemon cpu loved to do before i got new heat sink and fan(i was 64-66 celsius). stock heatsink and fan are horrible for cooling.
