Where is the HDD located on a Venue 8

Tablets usually have an "HDD" soldered on to the board. Unfortunately, unless you identify the storage chips on the PCB, there isn't a physical "HDD." It is rare to find a replaceable/upgradable storage drive on a tablet.

More appropriately, it might as well be called an SSD, but still.

If you can boot it up and trigger a system reset so that it clears the onboard storage and returns to factory default, you shouldn't need to worry about it. Otherwise, take a stab at random chips and see which ones hold the data.