Noctua includes a tube of Noctua NT-H1 TIM, which is a nice little freebie - it saves the $10 or so you would normally pay for thermal compound. Place a small drop onto the chip and spread it around using the heatsink provide maximum thermal conductivity.

Once you’ve got the heatsink mounted and in place, its time to attach the fan. You can use any 120mm fan you like, but the included Noctua NF-P12 ($20 street) is just about as good as it gets, and designed to be fully compatible. To attach the fan, first install the sound dampening strips. They are slightly adhesive and easy to install. Then, place the fan on top of the strips and it should stay there without having to hold it on. Once its in position, use the thin metal brackets to clip it onto the heatsink to keep it in position permanently.
If you’re using the NF-P12 in conjunction with the NH-U12P, you’ve got 3 choices in terms of power. You can use the direct connection, letting the BIOS monitor the speed (or just go full blast), the L.N.A (low noise adapter) or the U.L.N.A (ultra low noise adapter) - the latter two being reduced power, reduced noise adapters that let you quiet your PC’s operation. The trade off is that lower fan speeds bring higher temperatures, but Noctua gives you the freedom to figure out which fits your needs best.

I chose a direct connection. With the door on my case closed, there is no audible noise from the CPU cooler - even on its highest setting, its very quiet. I suspect unless this is going to be the centerpiece of an audiophile’s living room computer, the direct connection will be just fine.

So noise is taken care of - the NF-P12 is quiet. Like, scary quiet. The Noctua NF-P12 puts out 19.8 decibels of sound with no adapter, 16.9 dB with the low noise and 12.6 dB with the ultra low noise adapter. To put that in perspective, a quiet library is about 30 dB and rustling leaves in the distance is about 20 dB. I’m running two of the fans, one on the CPU heat sink and one as my rear exhaust fan - but not only are they quiet, they’re moving a lot of air. The unadapted airflow is 92.3 m³/h, which is more than enough to keep Intel Core 2 Duo e8500 running cool idle and under load.

The NH-U12P and NF-P12 combo enabled me to overclock the E8500 to 9.5×450: 4.275ghz. From the stock clock of 3.16ghz, that’s a serious improvement. That was the highest I could get before I began to experience stability issues. When compared to the stock Intel heatsink, the NH-U12P dropped temps more than 25° at base clock speeds, and the standard HSF was not enough to support any similar degree of overclock.