And that is not a good card. You can OC but it wont give you what you are searching for. Get a new GPU.
You can OC it with MSI afterburner. Download furmark to !
You use that MSI to up clock by 5Mhz and each time make a test with furmark for 10 minutes. You should check the temps . 80C shouldnt be touched. If you see any artifact increase the voltage by 10Mv and rerun the test. You should make a break of 5 minutes to allow the card to cool.