Quoted Text

Xbox 360s are manufactured and tested by Flextronics at their plant in Guad Mexico, known as Flex-Guad.
It is not the fault of Flex that these units fail, it is the poor design that went into them and Flex doesn't care because they are only paid to build it.

Flex runs many different products through their assembly lines for Cisco, Nintendo, Motorola, Avaya, etc and from TFA, other competitors to Microsoft don't suffer failures.

Xboxs are flawed in so many ways:
1) Restricted airflow over heatsinks using air dams
2) Awful heatsink design and little or no thermal paste between Asic and sink
3) The Asic they use are exposed die with no heat spreader
4) Microsoft tried to design their own GPU and processor themselves and failed miserably and hired a 3rd party to correct it
5) Use of lead free solder on their BGAs (very brittle and prone to low yields)

It is no surprise that many units fail due to excessive playing because the 2 main chips heat up to the point of warping the circuit board itself because it is very thin (cost cutting measure).
Microsoft placed the two hottest chips near the center of the board and it warps due to heat.  The solder balls crack when the board warps and you get those lovely E74 failures.  Turn it off, let it cool and it works for a bit until it warps again.

That x-clamp strategy used on the heatsinks was wrong to begin with.  The newer generation Xboxs use solid bolts instead of these locking pins.  If you have ever opened an Xbox you will notice those very LARGE capacitors littering the board which are prone to failure with the heat.  I have myself repaired Xboxes and can tell you those caps do not survive the removal process for CPU and GPU.

If you are a PCB designer and get a chance to see the XBox circuit board, you can see that Microsoft really didn't build a proper board.  They hired a team of monkeys to cobble together the Xbox and tried to fix thier mistakes 3 board revisions later.  Nintendo however, built a really nice board for low cost using proper design practices.