Bitmain APW12 upgrade
For using PSU in overclocked miners
Method 1: Add two resistors in FAN IC circut and wire jumper Step 1 Prepare PSU and parts for upgrade. And soldering tool. Hot air station. Step 2 For upgrade, you need to use two resistors 1206 size. Nominals of 56 Ohm 5% and 4.3 Ohm 1% and wire jumper 
Step 3 Disassemby PSU. Remove the top cover, carefully unscrew the board from the bottom of the case. Caution High voltage capacitors can be electrocuted if not discharged. 
Step 4 Carefully turn the board over and find the area where you need to add resistors 
Step 5 Locate near FAN IC two 1206 size resistors, on top of which you need to solder additional 
Step 6 Add flux 
Step 7 Use hot air station for add first resistor 56 Ohm. 
Step 8 Add second resistor 4.3 Ohm. 
Step 9 Locate near PIC IC 0805 size resistors R126. Resistor 1 kOhm. Can be marked as 01B or 01H or 102. 
Step 10 Replace resistor or just add wire jumper as on pictures Step 9 or Step 10. 
Finish Now you must assemble PSU in back order.
Step 3 Disassemby PSU. Remove the top cover, carefully unscrew the board from the bottom of the case. Caution High voltage capacitors can be electrocuted if not discharged. Step 4 Carefully turn the board over and find the area where you need to add resistors Step 5 Locate near FAN IC two 1206 size resistors, on top of which you need to solder additional Step 6 Add flux Step 7 Use hot air station for add first resistor 56 Ohm. Step 8 Add second resistor 4.3 Ohm. Step 9 Locate near PIC IC 0805 size resistors R126. Resistor 1 kOhm. Can be marked as 01B or 01H or 102. Step 10 Replace resistor or just add wire jumper as on pictures Step 9 or Step 10. Finish Now you must assemble PSU in back order.