the power supply is most important as well as your budget to determine what you can afford/run in the system.
we'll need to know the power supply model if it is good enough or a budget you can spend for a new gpu/psu. this looks like a pre-built pc which generally don't have very good psu's in them. but we need the psu model to verify. open the case and it will be on a label on the power supply itself.