You upgraded your GPU didn't you? Well you could have swapped the PSU as well.
Change it and hope that the GPU was not affected.
As for what to get, recommendations can be found in the first post here:
Below you will find MY standard list of recommended power supplies and beyond that this thread is intended as a landing place for questions or discussions regarding specific units, platforms or related PSU tech, all of which are all welcome to be discussed here. If it's related to power supplies...
forums.tomshardware.com
You should not go cheap on a psu as it's literally the heart of your system, powering your hard earned hardware. Pick a tier B and above from this
Tier list . An indication of a good PSU is the long warranty it offers. Almost all good one go with a 10 year warranty.
I would also recommend going for at least 650w and if you are thinking of upgrading to a more power hungry GPU in the future, 750w minimum.