Seagate 1TB Brand New. Sorry it would be disk manager but not showing. PSU thermaltake BM1, 600W SEMI MODULER.Welcome to the forums, newcomer!
Make and model of your HDD? Is it an older drive recycled from a prior system? Does the drive show up on a dock or a donor system? Make and model of your PSU? I'm assuming you meant Disk Manager and not Device Manager. Still is a good idea to check and see what you see in Disk Drives within Device Manager.