Intel 520 ssd disappears in startup manager most of times
I've replaced original hard drive with Intel 520 ssd. And It works completely strange. Most of time startup manager doesn't see it, sometimes it's visible, but disappears on selection. Sometimes everything passes fine and macbook loads from new drive correctly and fast.
If I'm trying to load from original hard drive ssd is visible and seems to be fine (visible, writable, readable, passes all tests and so on).
What could be wrong with it? Thank you.