Hard Disk Monitoring

Hi!

What happens if I tick "Do not allow spin down of disks" in Disk Control with a * and also have Sleep mode enabled at 4 hours? Will PC still be able to go into sleep?

Yes, the computer can enter to sleep mode.
The "Do not allow spin down of disks" option just helps to keep the drive awake when the computer is otherwise working.
This can help (for example) if the drive may have its own power management function which can activate independently from Windows power settings (eg. some external USB drives).