Have a look at your board and see if it has the same printed pcb and resistors as the picture. Also if you have a xfx card they like to use non-reference boards a lot so the design could be completely different. I would ask over at extreme systems, there's probably someone over their who can tell you what to pencil. That picture probably came with a post so get a multimeter and check to see if voltages are similar to what they are getting from a 4870. I wouldn't worry about it if i were you, pencil mods probably wont do to much justice, the 4890 already overclocks very well.