Area-51 R6, very loud

Check your CPU and GPU temps, make sure they are within a safe range (usually 20-40c idle, 45-70c when in use, depending on hardware). If your temps are unusually high for the task you are doing, make sure your ambient temp in the room isn't too high (computer not beside heat vent)....after that, I'd suggest checking case intake fan operation. Also check exhaust fan operation. Then check the CPU heat-sink. Make sure its seated. If you have knowledge of CPU removal, take the heat-sink off and check for proper thermal compound application. Don't attempt anything with the CPU heat-sink unless you know how to remove and reinstall a heat-sink. 

If your fans are running on high all the time, you have a problem with temps. So either there is insufficient airflow in the case causing the GPU and CPU fans to work harder than they should be, or there is a physical issue with thermal compound. If your system shipped with an overclock-able CPU and GPU, there is a chance something is wrong with overclock settings, so make sure before you do anything, set all clock settings to stock. If your clock settings are wrong, you will experience overheating.

If you're not comfortable attempting a repair, don't.  

Set to Manual and then Curve. Check which sensor each user-controllable fan is using.

Which fans are running fast? How many radiators do you have (ie, is your video card liquid-cooled also)?

Yeah, I'm definitely gonna have to wait for support or something.  I don't know enough to troubleshoot.  Thought maybe there might be an easier fix.  Thanks anyways guys.

I have the same system, and had the same problem.  Fortunately I work for Dell, and was hooked up to one of the Alienware gods.

We found out that the wires connecting the GeForce 1080 cards to the front liquid cooling radiators (fans - see photo below) were not tightly connected at the connecters, both wrapped in matte black tape.  With the unit disconnected from power, and with the card side open, I removed the matte tape on each of the connectors, and found that they were not fully seater together, so the connection from the fan sensors to the GPU cards was incomplete, causing the on-board fans to run at full speed.

Upon re-seating the connectors, and reassembling the unit, it worked flawlessly, and quietly, with the GPU fans correctly speeding up and slowing down as designed.

My brand new one has the same issue but the CPU is super hot 207F. This is the second broken product I will have to return.. I am so disappointed and a bit angry. Its been a onths since I ordered my first DOA one *would not even start up). Now this on the replacement. I doubt they will make this good.. spent 4 hours trying to get ahold of someone in the returns department. I am 52 and have been buying Alienware since they started so this makes me feel queasy. My original order was placed 6 week agoand still no good computer. sigh. 

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@OutOfControlPCIfan wrote:
intermittent PCI fan.
The PCI fan is the only one running out of control 

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As a work-around, in AW-CC , you should be able to tell the PCIe-Fan to watch the sensor on the CPU instead.

which fan is causing the noise? Use the Alienware Command Center software & you can see each fan. The second fan, the PCI is the only running out of control in mine.

Recently I've been in contact with

Adolfo Escalante
Tech Support
Social Media and Community Professional
Dell EMC | CSMB Technical Support Services
My schedule is Monday through Friday from 8 AM to 5 PM CST

And he tells me mine is a This issue has been tagged as unique, since other customers are not experiencing the same behavior as yours, reason why is taking time for them to determine the best course of action to take

So please everybody with a fan issue, please contact this guy so they know more users are having the same problems  technical_support@dell.com

The Dell techs, which I have been in contact with many & many have been remotely in my computer can not figure out what is causing it nor can they fix it.

The temp the Alienware Command Center is showing me is not correct for the PCI fan, it shows it very hot but I can touch it, it also has the fan running at 98% speed on start up & for days

How do you tell the PCIe-Fan to watch the sensor on the CPU instead? Non of the Dell techs have even tried this, nor have they replaced the sensor & sensor cable

The temp of my PCI is not correct, it says it is very hot & I can touch it. Nothing in the computer can control this fan. Many Dell techs have been in my computer remotely and can not control this fan.

"The temp of my PCI is not correct, it says it is very hot & I can touch it"

Touch what? What is your definition of 'PCI'? (Peripheral Component Interconnect is a device standard, not a device)

Install HwInfo, what do the CPU & GPU temps say