Motherboard is in great stress due to flexing of the motherboard.
How to fix it?
This is the X-clamp replacement method.
Note: Its is not a permanent fix.
What you need?
* M5 5x10mm Machine screws (8 Pieces)
* 5mm Steel/Zinc Washers (16 pieces)
* 5mm Nylon/Fibre Washers (16 pieces)
* Torx 10 and Torx 8 Screw driver to open the 360 and pull out the motherboard.
* Artic Silver 5 Thermal Paste (Other would work but your Xbox 360 may die soon)
How does it work?
Due to overheating the X-Clamps expands and the motherboard bends. This causes the error. With no X-Clamps and a fresh coat of Thermal paste on the CPU and GPU the Xbox 360 works. (Yea!)
Assuming you already know to open up your Xbox 360 if not, one google would help.
1) Pull out the both X-Clamps CAREFULLY. Use the method given in the picture (maybe some videos on youtube might help) .
2) Now, pull the heatsinks out.
3) Remove the screws on the heat sink using a spanner or a pair of cutting pliers.
4) Clean the shit (old thermal paste) initially using a tooth pick. Then, use some cotton dipped in alcohol (or any other volatile solution ) to clean the hard to remove stains. BE CAREFUL
5) The end product. Ooooh Shiny….
6) Smear some high quality Artic Silver thermal paste carefully. Use some cards etc.
7) Put the heatsink back as per the diagram. To do this, arrange the screws without the heatsink and tape them on the motherboard to hold the screws and washers. Now, place the heatsink and turn the screws, one by one.
8) See if it works (sometimes does)
if not (Avoid this as far as possible), Plug the fan, place the fan on the CPU and switch on your 360 for about 5-10 minutes (let the heat buildup), this lets the the Thermal paste bind between the heatsink and the CPU. Now, let it cool for about 10-15 minutes.
9) See if it works (Hope it does)
Optional Step: If your screw head is very thick and when placed on the shell, if the motherboard bends.Then, use a file to decrease the thickness of the Screw head. This ensure longer life.
Questions? Comments are welcomed.