Couple weeks back I got a request to repair a friends computer. It would lock up, not reboot, etc. The computer was largely for gaming, so after an initial software scan, I figured it must be heat. Opening the machine, I noticed none of the case fans are running. I had initially done the build on the machine, and new all the case fans were wired to the fan power “bus” provided by the power supply (which handled speeding/slowing the fans based on case temp), an Antec TruePower Trio TP3-550. Asking the friend, he mentioned that he had noticed the LEDs on the front case fan had went out a month or two ago. Hmm. Checking the voltage on that fan bus showed only 2V (not nearly enough to run a 12V 120mm fan). The PSU’s fan was also not running. Crap, that was probably overheating the PSU, and causing the instability.
Wanting to get his machine back up and running, I picked up a replacement Corsair power supply, installed it, and got him on his way. Then, I went to repairing the Antec power supply. Warning, because this is a power supply, and especially because this is a high wattage switcher, there are dangerous (and lethal if you live in parts of the world that run off 220/240 household) voltages inside. Make sure the unit is unplugged, off, and even give it an hour or two for the primary caps to discharge. I have seen the primary discharge relatively quickly, so there must be a bleeder resistor in the unit, but I didn’t bother tracking it down.