Before taking any initiative relating to Hard Drive, all the datas needed to be backed up since in case of maloperation, you may loose the entire data stored already and it would be hard to recover them.
PC supply should be consistent for an appreciable period since the entire process may take a longer duration.
There are certain points to be followed in course of operation and these are listed below -
1) You would need a PC/ Computer and a full version of software like Acronis Disc, Director 12 or an installed software on another PC and a reboot.
2) Shutdown the PC and then SSD is to be connected and select a new hard drive as second and third drive as second and third device with the existing PC Hard Drive.
3) Check in BIOs if both attached to Hard Drive are detected and BIOs shows all three drives.
4) Now clone the drive.
5) The PC may restart but that would not be a problem.
6) Ensure that no blinking of the electricity occurs.
7) After a few hours of operation, say for at least two hours, the PC is to be shut down and the second SSD and the third SSD New Hard Drives are to be removed. Boot the machine and check if OS is booting property.
8) If the OS does not boot property, check out the faults.