My second drive keeps disconnecting and I have to un plug and replug it in every boot.

I'm a first time builder and I recently built my first ever computer. Everything is working fine other than my SATA drive keeps disappearing every time I boot up my computer. It is very annoying and I dont know why. please help it was working fine on my old computer my friend built for me. I used the same cable to connect to my motherboard so I dont think its a cable problem.