I bought a cheap Zephyr board a couple of months ago, 0102 error, and last weekend I gave it its third heatgun treatment, yesterday played GOW2 for 20 min. and freezed, then RRoD. Besides this, I have done everything else, x clamp replacement, AS5, fan shorud mod, small heatsinks for upper RAM, southbridge and HANA, and finally a 70 mm front fan. Didn´t do 12 volt mod, but I guess it won´t do much of a difference since with the front fan, air coming from the back was warm, not hot............I´ve almost given up on this.
As for the heatgunning process, well, first time I followed the tut, but cam short on timmings since the foil was melting badly on high, and only did the top. However, the console lasted the longest time, like 10+ hours or so. Second time, was top and bottom but only GPU, 1 min low(250c), and like 2 min high(500c), lasted 3 hours of play. Third time I followed everything to the letter, but only did the GPU again. After heatgunning it always starts right up, but I´m wondering there could also be a cold solder joint under the CPU or RAM (0102 error), its unlikely since doing the GPU only has revived the box everytime so far, but I´m gonna try reflowing the whole thing next time.
Read about the oven method, but it´s scarier than the heatgun, will try if everything else falis though.......
Cheers.