1.1. PSU: The power supply is without function or the PC doesn't start
The power switch cable from the PC case is not connected to the mainboard.
The 20/24 pin ATX connector is not properly attached and doesn't have proper contacts.
The P4 connector is not plugged in (presuming the mainboard requires it).
The CPU is not properly attached to the socket. Memory is not compatible with the mainboard. (PCs can start without memory chips; if the mainboard produces post codes (beeps) then the power supply is OK).
Check that all PC cards are correctly seated into their slots.
The power supply's main switch is not switched on.
The main power cable is not connected to the power supply unit.
The multiple socket outlet may be defective, or need to be switched on, if a switch is available.
The mainboard may be defective.
1.2. PSU: The power supply restarts or shuts down
Insufficient cooling of the PC case causes the powe supply to shut down. Additional fans can prevent this problem.
The power supply unit is being overloaded by a retrofitted high-end component (e.g. graphics card). A stronger power supply cold help.
Lightning strike on the power network (overvoltage). The overvoltage protaction has been triggered. The Power supply should be able to restart again.
A large amount of dust cause high temperatures, which overheat the power supply. The PC should be cleaned from dust from time to time. Dust can even become statically charged and cause systems to crash.
1.3. PSU The power supply fan is too noisy
High temperatures in the PC case. There are too few fans mounted in the case.
The CPU or GPU fan is blowing warm air into the power supply causing it to heat up more than normal. Adjust the airflow in you case.
A cable got cought inside the power supplies fan producing a rattling noise. Use a cable tie to secure the surrounding cables.
1.4. PSU: My power supply fan does not work
You have a semi-fanless power supply. Some models start the power supply's fan only after certain load or temperature. Check your power supply's user manual to be sure.
Your power supply's fan is broken. You need to contact your dealer for RMA or replace the power supply if your warranty is over. Under no condition should you try to open the power supply and replace the fan by yourself. This can endanger your life. A power supply unit has high voltage charged insiede the capacitors even after it is unpluged.
2.1. CPU Cooler: Your liquid cooler makes bubbling sound
The liquid cooler is freshy mounted and needs to run a few minutes to settle the air inside the circuit.
The tubes are facing the upper side preventing the water tank to filter the air bubbles. This will not happen to a liquid cooler mounted on the top panel.
2.2. CPU Cooler: Your CPU cooler fan turns off or LEDs are dimmed
The CPU cooler is not connected to a 4-pin PWM controller on your mainboard. 3-pin controllers can only regulate fan speed via voltage regulation. If the controller sets the voltage below the minumum voltage of the cpu cooler fan the fan stops to work. LEDs connected to a 3-pin connector dimm when the voltate goes down. To prevent this make sure your CPU cooler is connected to the 4-pin PWM connector on you mainboard. Usually this connector is marked with "CPU".
If you are looking into an ENERMAX power supply through the fan blades, you may see special white glue on various coils. This is normal. It is a necessary left over from the production process and does not impact performance in any way.