Before we go, let's pull out the hard drive tray and take a look at the platter drive our mini came loaded with.

Tucked under the tray: a 500 GB, 5400 RPM HGST hard drive, coming in at 2.5" wide and 7 mm thin.

And on the top of the tray, a promising mounting point for a blade-style PCIe SSD, presumably what we'll find in a Mac mini equipped with Fusion Drive.