Dear your PSU would be requiring update. Remember your CPU and GPU would be drawing power from +12V so it must have 44Amps+. Check this PUS from EVGA. It will give you 49Amps on +12V and is 80+ Bronze Certified with 600W. It would be enough for your requirement.http://www.newegg.com/Product/Product.aspx?Item=N82E16817438014
Yes, with this upgrade GTX760 will work in this system.