Strange one I've never come across. Last week, my CPU fan and case fan (original issue, 2 years old) stopped working. Long story short: All 3 fan connectors on my motherboard seem to be dead. When I plug either fan into the PSU plugs (using a 5pin-3pin adapter), both work fine, but neither works from any of the three 3-pin connectors on my motherboard. Tried new fans, same story. Otherwise, my system works perfectly. Any ideas?