No limit.  But the old saying “don’t put all your eggs in one basket”. I would not get a single 8 tb hdd and put all data in it.  Multiple smaller hdd with back up seem safer. some more detailed tech spec of Seagate 1 tb and 500Gb hdd, spindle speed 7200rpm. [URL]
About to get an XPS 8940 with a 1TB M.2 PCIe NVMe SSD. I would like to add additional storage but am unsure as to what specification types of 2.5" and 3.5" HDD I can install? My present PC is 11 years so out of touch with HDD types.
XPS 8940, 1TB M.2 PCIe NVMe SSD, add additional storage