Reinstall the newest driver for that card. If it doesn't work, try your GPU to another computer if it's alive. If the same problem persist on the other computer then your GPU might be having a problem or dead.
If it worked there might me some problem with your power supply. It might be unstable or failing. GPU is a power hungry hardware. It's the first hardware to show signs and symptoms next to the monitor when a PSU is failing.
BUT before resorting with the PSU, don't forget to rule out everything first as it might also be caused by other parts.
Issue you might have:
- Failing GPU (it doesn't really matter if new)
- Bought a new PSU which is failing too. (happened to me)
- Graphics Card driver
- motherboard or CPU problem.
Few test you can do:
- test your GPU to another computer
- test your PSU to another computer
- clean install your graphics card driver
- check if something's wrong with your whole PC specially the mobo and procy part.
Since you have parts ready, your friend's PC or a stock PC might be a great help. Just a little bit warning about the PSU testing, make sure to isolate it from your system before clip testing or it will fry everything connected to it.