Hello! Got an 820-3115 here with quarter fan spin. Already verified all current sensing resistors around ISL area, replaced ISL, replaced clock chip but no luck. I get steady 3.3V on L7220 and steady 12.54V on PPBUS_G3H. Get a sparkle of 5V on L7260 when quarter fan spin. Already verified all traces around ISL and all look good. There was no corrosion at all on this board! I'm lost, because this is the first quarter fan spin that is giving me so much trouble!