XPS 8930, recommend 2nd hard drive?

Any 4TB SATA 6 Gb/s hard drive should work, but the one you mentioned runs at 5400 rpm. I think I would pick a hard drive that runs at 7200 rpm. 

@ChumFighter 

Can someone recommend a 4TB hard drive that is compatible with the XPS 8930?

Any 3.5" SATA 6GB/s HDD.  I suggest Western Digital (WD) Black HDDs.

Pick an available make and research the model specs to pick a model.  Then source the equivalent model (model numbers can vary slightly with retail source) at the best price... usually a bare drive with no other bits, but not always.

For example, if you pick WD Black HDDs, you can research the model specs here:

https://www.westerndigital.com/products/internal-drives/wd-black-hdd

https://documents.westerndigital.com/content/dam/doc-library/en_us/assets/public/western-digital/product/internal-drives/wd-black-hdd/product-brief-western-digital-wd-black-pc-hdd.pdf

Notice that the 4TB model WD4005FZBX (second link) has the best interface transfer rate at 256MB/s, so that could be a model worth sourcing.

Finally, try to find a positive user review online that may confirm, 'fast, cool, quiet, energy efficient' (notice that the larger capacity drives may have slightly louder acoustics).

Open the XPS case and measure the SATA data cable length required and note the end connector orientations that will fit and route the cable best... buy a quality SATA data cable that long with those end connectors to go with your new HDD.

In the US, check Amazon and Microcenter.

GK

To add to what @GKDesigns I suggest that you consider a right-angle SATA cable. When the HDD is mounted to the drive cage at the bottom of the case, if a right-angle SATA cable is not used, the connector may interfere with closing the side panel.

@ChumFighter  how do I remove this black plastic piece?

While gently lifting on the graphics card, grab the top of the support bracket and rotate outward. It should pivot on that bottom foot.

 how do I remove this black plastic piece?

Here is a YouTube video where the guy removes the bracket at about 7:05 minutes into the video: https://www.youtube.com/watch?v=IEVrA1sufqU