SanDisk Ultra II SSD 480 GB SATA III Internal SSD will only works externally

[ampdvodka]

As the title states, I have a SanDisk Ultra II SSD 480 GB SATA III 2.5 inch Internal SSD. I have an abundance of cables at my disposal and so have tried multiple different cables internally but this SSD will not show up in my BIOS, Disk Manager or Device Manager. It just does not seem to exist on my PC. As stated I have tried multiple cables, as I have also tried multiple 6G ports as well as SATA ports. Nothing.

However, if I plug the drive in externally then it works perfectly fine and shows up fully. I feel like I'm missing something blatantly obvious here, but the SSD does state it is an INTERNAL drive. Yet it only works externally. I'm baffled. Could anyone shed some light on what the problem might be please?

 

[CountMike]

Maybe a stupid question but are you connecting SATA power cable to it too ?

 

[ampdvodka]

Maybe a stupid question but are you connecting SATA power cable to it too ?

Yep. I am using a SATA cable on it's own though. I had no open slots available on my other SATA power cables so I plugged in another just for the SSD. As stated, I have tried multiple different SATA both for the power supply and to the mb to account for cable faultiness but to no avail