They are basically an industrial sized fan that supports 6 to 30 volts. I would get 12 volt fans, as the 24 volt ones are for use in industrial environments and not home computers.

A PC power supply, including the ones that Alienware uses, does not provide a 24 volt plug. It's typically reserved for server grade PSU's.

The new NF-F12 (120mm) and NF-A14 (140mm) industrialPPC-24V models use a dedicated wide input range version of Noctua's NE-FD2 three-phase motor driver IC. Supporting operating voltages from 6 to 30V, these models are ideal for 24V-based industrial applications and voltage-based speed control. All new models feature IP67 water and dust protection and PWM.

“As our industrialPPC models have become quite popular among PC enthusiasts, we think that the new 24V variants can also be interesting for PC users due to their wide input range”, explains Roland Mossig (Noctua CEO). “When you run them at 12V, you will get much lower speeds and noise levels, so they combine the advanced features of the industrialPPC line with the renowned quietness of our standard line-up.”

While the industrialPPC 24V models have been designed with 24V industrial applications in mind, they run at maximum speeds of around 1100rpm (2000rpm models) to 1700rpm (3000rpm models) in 12V PC environments. At the same time, they can be slowed down further via PWM, thus combining the advanced features of the industrialPPC line with Noctua’s signature quietness.

Awesome. Thank you so much. Do you know what is the best fan for Aurora r10.

which have a better airflow and static pressure. 

That I do not know. There's some threads on this board that discuss some aftermarket fans. Corsair fans seem to be working well, although some have reported good success with Noctua fans.

They should be a few pages down.

I am a firm believer in Noctua products.

Not really sure (benefit wise) why someone would want to put a 24v fan in the Aurora.  They sell standard 12V equivalent options for the 12V headers in the Aurora. 

The IPPC 3000 is a server grade fan for high pressure applications. 

Note that the OEM Dell Nidec moves a fair amount more air than the Noctua F12 IPPC 3000 (149 vs 109 cfm).  Not to say that the Noctua's 109 is bad by any means it's really good.  I have two IPPC 3000 fans in my Aurora. 

Most people don't like the OEM Nidec fan because it's noisy (and at 5500 RPM it can get really noisy).  Not because it has poor airflow or is a bad radiator fan.  It is a good radiator fan, it just isn't designed for quiet applications or have all bell's and whistles of premium aftermarket fans. It's like a jet engine at full throttle.