# of not-in-use PCIe slots on Alienware Area 51 R4?

I'm looking at buying an Alienware Area 51 R4: i9 7900X CPU, 64 GB RAM, single GPU (1080 Ti), dual hard drives (512 GB M.2 SSD boot and 2 TB SATA storage), 850 W power, Killer Wifi. I need to know how many not-in-use PCIe slots the desktop comes with. I have a document which shows that there are 6 PCIe slots (3 x16, 2 x8, 1 x4) but, for example, I know that the 1080 Ti will occupy at least one of the x16 slots. I need to know how many will be available. I've contacted Dell Support three times about this and have gotten three different answers, so some clarity would be greatly appreciated!