Also the hd5570 and hd5670 does not want any power cables.The get the energy from the Pci slot
AnD be careful when you put the new video card in CHECK YOUR PSU AMPERAGE
You have to give the hd5670 5 AMPERS
The 7770 only uses slightly more power than the 5670 and the 6670, so switching it out for them is not a good idea as an attempt to avoid needing a new PSU. Pretty much any video card except maybe something like a 6450 would be best with a better PSU.