This is an older thread, but I just wanted to chime in for those considering the Liberty fan swap.
I have the Liberty 620 and unless my model is different the 3-pin connector does not have the same layout as a standard 3-pin fan. The red and black wires are reversed. Normally, a fan goes [RPM]-[RED]-[BLACK] where as the Enermax Liberty connector goes [RPM]-[BLACK]-[RED]. If you look closely, you can make this out in the photo posted in this thread.
I did not notice this at first and when I plugged in the removed Enermax fan into my power supply to examine its noise characterstics, the fan was immediately fried.
I ended up cutting off the connector on the Enermax fan and making an adapter from one of those 3-pin to Molex connectors you get with most fans. This way, I did not have to mod the fan I put in and it gives me an easy way to try new fans with the Liberty if my initial fan attempt doesn't work.
At this point, with the original Enermax fan toasted, I had the necessary motivation to go forward with the fan swap
I started with a Scythe SFB-E (1200rpm) fluid dynamic bearing fan. This fan is extremely smooth with almost 0 bearing noise and good airflow at the full 12V. Unfortunately, when I booted my system the fan was not getting enough voltage to start. Since the Liberty doesn't even send 5V until somewhere after 150W, this was understandable. I ended up trying a Yate Loon D12SL-12 next. This fan has a higher top-end at 1350rpm and starts at a wide range of voltages. Surprisingly, the Yate Loon did not start immediately, but after 2-3 minutes gets enough voltage and begins barely spinning. The power supply remains cool to the touch (bottom chamber of P180) and the exhaust air is only slightly warm. I would prefer a fan that starts immediately, but I am willing to give it a try. My systems stays on 24/7 in a hot apartment and is subjected to multiple users and gaming, so I think I'll know in the short term if the fan isn't providing enough cooling.