Before making any purchase two things are always advised first, get the present GPU tested in a computer that has an appropriate quality and spec PSU or ask a local tech/tech store to test the GPU for you, reason for this is that using a weak PSU over a period of time damages any hardware that relies on it for power and the GPU being the most power hungry suffers first and tends to suffer the most, you don`t want to go to the time, trouble and expense of getting an appropriate PSU only to find out that the GPU has been damaged.