If it came out of a laptop that was set for UEFI mode then it's possible that the drive is set up as a GPT partition type. Most Windows 7 machines had Legacy mode as standard which use the MBR partition. Your R2 only has the Legacy option while later machines had the option for Legacy or UEFI in the BIOS.  Is the drive detected in the BIOS? Even if it is set up wrong it should still be seen in the BIOS. If it isn't in the BIOS then there's another issue.  If it set set up wrong then it's easy to change it but you will have to reinstall Windows if you want to use the drive as your OS drive. Do you have the original Windows 7 installation CD that came with the M17x? If not, you will have to find the ISO online and install it onto a bootable USB drive.  Let me know and we can walk through the process of reinstalling Windows and changing the partition type to MBR using CMD and Diskpart.  
Hi all, I have an Alienware m17x R2 (specs below) I have an SSD from a laptop with Windows 7 and was used as the primary. I have tried to use it as my primary for my m17x R2 but bit is unrecognised and presents a 'no os detected. I might be missing something very obvious but can anyone shed any light on this? I'm guessing bios or (hopefully not) wrong format. Thanks in advance 
m17x R2, SSD not recognised