I just got a Thermal Take Spark 7 for my 2.4c running at 3.0ghz. Its a copper design with a 1300-6000 rpm adjustable fan
I wasn't having a heat problem, but I like new toys.
Well, at 6000 rpms you better put on some headphones cause this thing is noisy. It did drop my average temps about 9 degrees though.
Under load I was getting about 132 F and it dropped it to the 122-124 F range under load AT full RPM . I am currently running it at 2722 rpm and getting about 4-5 degrees cooler temps.I can't hear the fan at all at this speed. Running a game I am sure I could turn it up a notch or two and still not hear it but my temps are well within range.
So you can may be able to go cooler, just don't expect anything drastic without cranking the fan up.