just replaced my cpu cooler with an h80i v2 yesterday. It's a tight fit and the screws are short but it worked great. My first replacement was an H55 (almost identical to the original).

I hear the noctua's like NF A8 PWM are options for replacing the PCI fan

H80i V2 is a tight fit but worth it. You can even find some video in youtube on how to install it. I had the fan noise problem too, Alienware Therma controller does not really work well with Windows 10. My solution was to use the Corsair Command Pro. Please take a look to this discussion link.

https://community.dell.com/thread/25116-aurora-r4-fan-noise-reboot-start-up-option-solved

Rhenium also recommended he Noctua Fan. I have not tried yet but I can tell that the Corsair Command Pro with the software Corsair Link gives extended flexibility not only for the pump/cooling H80i V2 but to independently control any fan attached to the corsair hardware and you can also create profile.

I revived an Alienware R4. Use Noctua NH U9S. It's a very silent cooler and whenever I play Deus Ex, it never sounds.

I prefer air cooler as reliability > performance. Air cooler makes maintenance much easier.

I use an after market Mobo (ASUS Z270G). So I hook my NH U9S to my mobo and an iPPC 2000 PWM to my mobo.

I attached three NF R8 Redux to the top vent filter and mask them as PCI fan, memory fan and CPU fan. NH U9S goes to my ASUS mobo.

Finally, I replaced the HDD and PCI bay fan with NF B9 Redux.

iPPC 2000 PWM is a poweful fan and may be noisy. You can try is NF S12B or NF F12 PWM.