A question.

[hameedabdul1]

I'm trying to build a NAS with a Raspberry Pi 3 B+. The thing is, I want to use internal Hard Drives, because I already have them, as well as a PSU. The problem is, I need help with getting sata data cables to usb. Ones without power attached, because that's what the psu is for. I would love to know if my extreme idea is possible, because I am really not trying to spend more money than I already did for this thing. 

[bowrilla]

1st Choose a proper and meaningful title. "A question" is basically the most generic title possible because almost EVERYONE creating a thread has a question.

 

2nd Have you even tried Google? You're not the first trying to do something like that. You won't find a cable to do the job, you'll need a SATA controller. Which is basically what an external drive offers. 

 

3rd switching on the PSU is easy. Just look for the ATX pinout. You only need to bridge a certain pin to one of the ground pins and the PSU turns on. You could use the GPIO pins for that. But since you're asking such a basic question I assume you have no experience with electronics so be aware that you might get a shock if you play around with stuff like that or you might destroy some of your components. DO NOT open the case of the PSU. That can be deadly.

 

4th It would probably have been cheaper and more reliable  and probably even faster to buy an old prebuilt on craigslist.