Startup after new psu

[ThatGuy_2]

I have no idea what this means, its just telling me this after I just installed my new psu.http://

Edit: This was after my old psu overheated, and my windows 10 install might be on my external drive. But I have the external drive plugged in.

 

[Emerald]

it is not finding you OS

 

[Ari3l]

Maybe somehow your BIOS settings got reseted? Go on it and set the external drive as primary boot device.