You'll have to do a clean install of Windows and apps on the new SSD after you disconnect the HDD.  When that's done and everything works, you could reconnect the old HDD to see if you can recover any personal files that aren't backed up elsewhere. You will need an extra SATA data cable to have both drives connected at same time. The PSU should have several SATA power cables attached to it, so that's not an issue. No guarantees you'll be able to recover anything from the HDD. NOTE: you probably will have to use the F12 boot menu to select the new SSD as the boot drive after reconnecting the HDD. Otherwise the PC will always try to boot from the HDD and it will fail, if you try to boot "normally". When you're done trying to recover files, disconnect the HDD again and you'll be able to boot "normally" directly from the new SSD.
My hdd just died. When I try to boot up, I get a black screen but with the Windows startup sound and just hangs forever. It’s running Windows 10 and I would like to run an SSD and retrieve my files, if possible. Do I need to upgrade cables? What are the procedures to retrieve the files?
XPS 8300, error code 2000-0142