Hey there, aries1357!
Have you tried reseating the SATA cables to the HDD(s)? Make sure every connection within the case is plugged properly, if you encounter any issues with that, refer to your motherboard manual.
The problem might be in your new PSU because it might not be supplying power to the hard drive. You can try using a different cable to connect the PSU to the HDD. Also make sure the boot priority in BIOS is properly set.
You can determine where the problem comes from if you plug the HDD on another computer, see if it gets recognized there.
Check this thread for other troubleshooting ideas:
http://www.sevenforums.com/hardware-devices/259192-psu-died-new-psu-bios-wont-recognize-sata-devices-now-wont-turn.html
Good luck! Keep me posted!
SuperSoph_WD