Anyway, despite that foray off the beaten track here, I recommend an aftermarket HSF for your machine. The logic is this, you can run it too hot, but you can never run it too cool. If the machine plops along at 40 C while tasking, I'd be thrilled. I set my BIOS CPU temp warnings @ 60c, and during our 100 F + heatwave, they tripped, this using a very modest aftermarket HSF, with a Matx case G41 Matx board, and a Pent dual core E6300. A few wires were rerouted, and the front fan cranked up to max, goodbye nasty case speaker noise.
If you can get the Cooler Master tower I pointed out at a reasonable price, grab one, otherwise invest into something more exotic. The cooler it runs, the longer it lives, period. The bottom line here is, you've invested into a fairly high end machine, why cheap out now?