Aurora R8, adding a new hard drive

Thanks - I'll actually be installing a normal 7200 RPM disk drive . . . does that change anything?

The PC comes with a power cable to connect to a 2.5" sata drive. 

You need to buy your own sata data cable if not included when you buy the drive.

You can go higher than 2tb on a storage drive as long as you set it up as GPT and don't set it up as MBR.

SATA drives (3.5-inch spinning platter HDD and/or 2.5-inch SSD )

... need both a SATA-power cable and a SATA-data cable.

We have no way of knowing what Dell might have pre-installed for future expansion.

I suggest you get the PDF Service Manual, and compare to what you see inside your exact machine.

And no, there is no 2tb drive limit on this (UEFI / GPT) machine.

If your adding a Sata Solid State Drive you'll need a sata cable, the power is already in the harness. Like add a 2.5" SSD the cage 3 you'll need the sata cable from ssd to motherboard and then hook to your sata3 on your mobo. 

No, doesn't change anything. The 2.5 hdd needs a power cable, so does a 3.5 hdd or 2.5 ssd, Or 7200 rpm hdd. But it's included so you're all set either way.

My R9 came with a single drive M.2 NVMe 2 TB. the 3.5 hd spinning hard drive already has power and sata cable on harness. Open it up and see I dont know about the R7 and R8.

I noticed your response to an earlier thread about drives on the Aurora R8. I have a 3.25 TB WD Red 10TB drive that I want to add to mine if possible.  I have a 2 TB m2 and a 2TB 3.5 in there already. Can you only fit 1 x 3.5 hard drive in there? Cant I add a third drive? Thanks in advance for any assistance. It is a brand new machine delivered yesterday...

There is only one 3.5" hdd caddy in there.  You could buy another one, remove the 2.5" caddies, and try mounting it under the GPU.