Well there are a few things I can think of:

1. Overclocking is okay but overvolting is bad for the card in that it shortens the lifespan. However, if you overvolt and get stable settings that is fine but your cards life nad warranty will be reduced. I fyou get stable settings your should always stick with those and never get passed them. Make sure you find a limit where you don`t have to overvolt.

2. If ther were lights and flickering chances are your card burned a few components and you overvolted the card too hard. The components are made to take a certain amount of straina dn you may have gone passed that point.

3. Your PSU is way way way low for the card you have. You can have a 430w PSU and expect to overclock. That was definitly one of the things that factored into teh whole mess.

My suggestion: BUy a new graphics card and a new PSU. But dont mine with you GPU because its not worth it anymore