If under clocking fixes it, chances are the card has a defect.
You can try 39mhz under to see if it is any better. Nvidia cards(Kepler and newer) tend to go 13 at a time making your 30 into 26 instead.
If that fixes it, I would high recommend you RMA the card or at least get some diagnostics with the cards maker.
I have noticed that some of the cards do in fact boot higher than they can maintain stability.
Thanks, I'll look into an RMA after I conduct more tests. Just want to make sure that it's definitely the GPU.