I've done the full 6800U mods...lol...I still sold the card

If you have never done vmods before, I would really suggest trying one on a less exspensive card. VMods are nothing like BIOS flashing.
Also, you can edit the 6800U BIOS to accept up to 1.55v, which would help. Anything over 1.55v and you'll need really good cooling.