When you put the MX4 on did you remove the double sided tape entirely? I'm not an expert with the stuff...just ordered some off ebay...also how do you determine how much to apply? Do you have a pic that shows how you tapped into the power to supply the fan?
Yes I did. My usual routine is to peel off what I can, then a drop or two of WD40 if needed to get all the glue off. Then wipe it with some alcohol (degrease it). Then a tiny dab of thermal paste, just enough to cover the chip when compressed (or super glue ;p ). Not rocket science, too little is better than too much in this case, but either will be fine. Don't be afraid to pull the heat sink off to check coverage..
I don't have a pic, but grabbed one off of dd-wrt that shows the back side of the circuit board. I added the + and - connections I soldered to ( power plug input, bottom left corner ), but be sure and check the polarity with a meter.