You guys do realize I'm an IT guy right? As I said before, I simply booted to a different drive in the same system. No changes were made to anything because with my BIOS if there is a failed boot it reverts to other settings. For example - If I overclock too high and it crashes it'll boot to safe clock settings so I can change the overclock to a safer level. When I get the beeps and code FF I just press reset and it boots to the next drive in the boot order (with my overclock intact). It's really an awesome BIOS. IF it isn't my main drive, then it is the SATA port that it is connected to.
When I get my spare drive from my Dad's I'll make a fresh install (I'm overdue anyway) and back up my files from that main drive (Yes I do it manually, I hate backup utilities). Then I'll run some diagnostics to see if I am correct that it's the boot sector, or possibly the SATA port (though this is very unlikely as I can still access my files, but who knows). If it's the boot sector I'll just repair it and be able to boot into it like always. But if it's the SATA port I should be able to just switch to another port and change the boot order in the BIOS.
TLDR: The only thing that's different between not working and working is the choice of drive to boot, thus all other hardware besides my main drive and the SATA port it's connected to is ruled out. And it IS hardware related because it doesn't even POST, and that rules out software.