I was going to try this to see how much of a jump I would get but I am not a dos person so when it came to running the nvflash I had to stop. Just don't know the commands.
There is a nvflash which works from windows, I used it to flash several times my cards and never had any problem.
I used this one from here
http://www.overclock.net/t/1438886/official-nvidia-gtx-780-ti-owners-clubIt is in the Ez3flash.zip (ez3flash being a bat file which uses nvflash)