Why is my replacement SSD not recognized by OSX?

I purchased the OSX Server, not realizing how slow the 5400 RPM hard drives are for running programs. I have a mac book air with a similar processor and SSD, and it flys! So I figured if I took one of my SSD's out of a PC that it would work. Well, I took out one of the two 1TB OSX hard drives out and replaced it with the SSD. And so far no matter what I cant get OSX to recognize it durring recovery as a drive, or have it recognized in OSX once booted using the hard drive cable that was attached to the 1TB drive and the mother board connector.

So I put the computer back together, feeling defeated, then remembered that I might be able to plug in a sata to USB 3.0 converter and voila I'm now booting off of an external SSD drive for the last few days.

My question is why wont it work using the internal connectors?