Microsoft really made a mess with the XBox 360 for a number of reasons:
- Poor hardware designers
- Poor mechanical designers
- Poor choice of hardware / component placement
- Lack of experience in designing ASICs
- and a lot of others.
If you have a hardware or PCB design background you would understand. Here are the reasons:
1. Having said that, if you crack open an XBox the first thing you notice is these huge bulk caps of 4700uF each (about 10+ of them) across their power planes. Is there so much noise in that unit you need that many huge caps? Apparently so!
2. If you remove the heatsinks, you find both ASICs have an exposed die. There is almost little or no thermal paste between the die and heatink. What they are missing is a heat spreader/lid which should be glued to the processor/gpu but no, that would have cost them an extra dollar or so. Since both ASICs have thermal diodes inside them once a critical temperature is reached, the unit stops working with a thermal alarm --> possible E74
3. Poor choice of heatsink mechanicals. They hired a bunch of monkeys to spec out their mechanicals. The X-clamp was the worst choice ever since is caused boards to warp, ASICS to lose connectivity due to cracking BGA solder balls when the temperature went up.
4. Poor feedback from their contract manufacturure who built and assembled the PCB and hardware. The people working on the assembly lines at the CM in Mexico don't provide feedback enough to the designers. If they noticed a lot of units were failing with thermal alarms or poor soldering (poor yields for that matter) they should have told the hardware engineers. Eventually, someone on the hardware team clued in and the heatsinks were changed and the x-clamps vanished and were bolted down instead.
5. Use of lead free solder. Why they chose to use a lead-free solder process is beyond me. The thickness of the PCB is already thin and they have to use extremely high heat to solder the ASICs down to the circuit board. Coupled with the terrible heatsink design/implementation you get a thermal differential on the circuit board causing it to flex. When the XBox is on and it heats up thats what you get, the circuit board warps and some of the solder balls crack because the lead free solder is brittle especially at high temperatures.
6. Microsoft learned first hand they stank at ASIC design. The tried to design the processor and gpu inhouse and learned very quickly they were terrible at it. After a horrible first run, they decided to hand that over to a design shop who knew what they were doing. However, they still need to learn how to package ASICs properly.
The most common issue is with heat, and you all have read the RROD fix using the towel. Which is a poor mans attempt to solder an ASIC that has 1200 solder balls. In short, you restrict the XBoxs airflow while it is on, allow it to heatup in an attempt to get the solder to go into re-flow while the temperature of the circuit board climbs beyond 150 degrees while everything is running. Mind you the components inside aren't even rated to operate reliably at those temperatures. So even if that fix works for you, you have just cut the life time of your unit in half or less because you caused damage to all the components inside by allowing them to operate well beyond their rated maximums.
So if your unit operates when its been off for a long time and dies shortly after being turned on, congrats you have soldering problems on the key ASICs. Take it back to the store and tell them its a manufacturing defect because it is!
Microsoft sends it back to the CM and they strip it down and run it through the machine that solders the ASICs down using hot air or a confined infra-red source nozzle.