XPS 8920 - Can I add a second SATA Hard Drive?

Hello all - I recently bought the above mentioned system with the out of the box specs - no SSD. Upgraded from last machine XPS 420 and need to get some data from the old drive. Just checking to see if there's a second bay in the new computer and if it's compatible regarding size and power and data connectors before opening the box. I did check the service manual but I'm visually impaired and can't make out the diagrams very well, and not sure about the descriptions (SATA vs SATA6 and so on). This is the main issue, but I'm also wondering about the expansion slots such as PCIe and whether or not they're the same. Thanks in advance!

I didn't find the right solution from the Internet.

References:
http://en.community.dell.com/support-forums/desktop/f/3514/t/20013500

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