When you replaced the hard drive, did you clone the old system or do a
clean install? If the latter, did you install the drivers for all your
hardware, including the motherboard, sound and video cards, etc.? If
not, you need to do so.
If you did install the drivers, then perhaps you dislodged something
inside the computer when you replaced the hard drive. With the computer
turned off and unplugged, open it and reseat all the cards.