One look at an RRoDed Xbox 360

Keywords: Xbox 360 RRoD solder problems
Although this picture doesn't have the better detail possible, you will still be able to see what is the problem that is affecting most, if not all, Xbox 360 consoles that suffer from the dreaded RRoD.
This is a small picture of one I have here, from underneath the motherboard, which shows many solder points that have developed holes, literally. This has happened massively throughout the board: probably 20% of the solder points are in some kind of bad shape, be it with holes or becoming brittle, while some look fine.
The problem stems from the type of solder used, a lead free type, which didn't have a very good formula. That, coupled with the bad clamping mechanism and heat, results in damaged motherboards and GPU or CPU contacts, and causes failures most of the time. It can also be a problem with the southbrige or the scaler chip, as error codes, usually, point out.

Temporary fixes can be done, like the "towel trick", but more permanent solutions demand exchanging the clamping mechanism or heating up the board. What those techniques do is heat up the solder, so that it eventually expands enough to the point it establishes some of the lost connections, resulting in a working console.
You can see that most people manage to achieve that, for a long time, if they exchange the clamps with screws(results in the first post).

While people were discovering a strange towel method and others doing more clever stuff, Microsoft threw epoxy at the chips. The big problem isn't that the chips are warping with the heat, it's the heat and very bad solder. The extra heatsink they have now in the GPU cooler may have helped, lately, but it's not the final solution.

I'm also investigating the possibility of capacitor failure, but for now it's not conclusive and if it does indeed exist, it should not be a major problem. They have changed some of the electrolytic capacitors close to the GPU to polymer based ones in elites - a good move given the close proximity to the hot GPU cooler - but they have also reduced them from four to two. Given the bad quality of the solder, in rare occurrences, bad connections in many components of the motherboard can also be a cause of failure - Heisenbugs, like Bunnie points out.
Recently I've had to re-solder one capacitor on a graphics card, which apparently was without any problem. Some motherboards may also suffer from this, from time to time, sometimes exacerbated by bad cooler retention mechanisms.

Hopefully the upcoming process shrinks - like with the current Falcon model - will bring the failure rate down. Still, this massive failure rate is unacceptable for a company as big as Microsoft. After doing a very interesting work on security, the option of saving cash with a cheap type of RoHS compliant solder turned out into a $1 billion dollar fiasco and not very happy customers.