odd hdd issue

[tacticaltech]

ok, so I have a Seagate barracuda 1tb hdd. just did a full format in disk mgt, and shows 931.51gb free. full capacity. then I restart my pc and sometime later, I notice I have 1.37gb of space taken up by an invisible something. nothing shows in disk mgt, nothing in file explorer, not even with hidden items shown. wtf? not that it matters, but sys specs are- 3770k, biostar tz77xe3, 16gb vengeance, wd blue 500gb boot drive, aforementioned Seagate 1tb, 120gb sata1 drive for lolz. also wd mybook 1tb usb2. ive scanned entire pc at boot with avast and malwarebytes -both free ed. nothing. win 8.1 fresh install...think that's all I got. is this possibly the hdd self correcting bad spots? disk chk shows no errors tho.

[flibberdipper]

System reserved or something along those lines, most likely.

[tacticaltech]

never seen any other drive do this. not sys reserved, as that shows up as a separate partition. this is just used space, but doesn't show as a partition, or any identifiable data.and shows as 930gb free of 931.51. so not the drive "shrinking " from bad sectors or whatnot. not a pagefile either, since with 16gb of ram and no ssd, I turn them off. still got me baffled. one for the gods to answer.