The process is similar:
Use an application like MSI Afterburner or Asus GPUTweak
Up the powerlimit to probably +20%
Up the GPU core speed by a bit at a time (say 10-25mhz) and test for stability with 3DMark or Unigene Heaven/Valley. If it is stable, up the speed a bit more an re-test. Keep going until it crashes/artifacts. If that happens up the voltage by a bit on the card by 10-20mv and re-test. If it is stable add more speed. Rinse and repeat.
Once you found your top speed of the GPU core, proceed to do memory. Reset the gpu core back to stock settings and do the same process as above but up the memory speeds and re-test/up voltage re-test, etc.
Once that is complete. Put your card back to the highest stable settings that you found and subtract 5-10mhz from each for edge-of-stability purposes and test and see if it is stable. If it is, then you are good to go.
Note: Make sure that your card is staying cool enough (with your waterblock it shouldn't be an issue).