7900gt vs 7900gtx :S

7900GT is a GTX with lowers voltage. Do the 1.4voltmod, and run it at stock GTX speeds. Both of mine run at 650/1800 after doing the 1.4voltmod.
 
One way to go is two 7900GTs in SLI, it's the same price as a single 7900GTX but out preforms it, especially at the higher resolutions.