What diagnostics software do you use for Windows (7 and up)?

Looking for recommendations of hardware diagnostics utilities, that check things like processor, memory, disks (HDD/SSD/CD/DVD) and other peripherals. Used to use such utilities a lot earlier, both for work (partly when a system engineer, but mostly on Unix) and for learning/fun, and had written a rudimentary one or two, but haven't been using them lately, so not aware of current ones. Could include ones built-in to the OS or third-party, and free or paid.

Thanks in advance for answers.