Only RED dimms work. 😛
There are 4 slots and so 16 gig is max dimm size.
I recommend Matched ram sets.
DDR4 PC4-24000 • 15-16-16 • Unbuffered • NON-ECC • DDR4-3000 • 1.35V • 1024Meg x 64 •
If you do go for the 32GB or 64GB RAM at 3200mhz, make sure you enable XMP in either the BIOS or Alienware Command Center (in Fusion, enable an overclock profile and the settings for the RAM at 3200mhz should be the second profile).
My Aurora R8 did not have XMP enabled out of the box, so double check your system when you get it.
Memory and GPU prices have come down that it makes more sense to BYO rather than buy turnkey at this point.
This isn't necessarily true anymore.
I know this is Dell's forum, so let me be clear that I am not a Dell/Alienware employee nor am I shill.
With sales, employee programs, discounts and other price reductions, you can get an Alienware desktop that is either slightly more, equal or less in money to parts picked out to BYO. I'm actually surprised that pre-builds have considerably come down in cost because 10 years ago BYO was absolutely the way to go. I've built 7 computers and I just purchased my first Alienware desktop a week ago. I'm no longer going the BYO for a variety of reasons.
GPU prices are still very high, granted not as high during the mining craze but still beyond what they should be priced IMO. 5 years ago you could have gotten a top of the line GPU for around $500 and now its doubled. Memory prices are still high as well. Storage, on the other hand, especially SSD's, are pretty cheap.
The other factor is the technology speedbump.
$170 GTX1050TI is as good as the $500 GTX 680
Even the GT1030 is fine for low end