Ok, I just bought a new case from Intrex computer store, along w/ a 400W PSU. Now, I screwed it in, and just connected the power connector in and plugged it into the wall, I flipped the switch, and nothing happened. The fan didn't spin. Does this mean the PSU is faulty? I watched the guy at the store test it right in front of my eyes and it worked fine. Does the 20 pin connector have to be connected to the MoBo for the fan to spin?