Several years ago, the semiconductor industry moved to lead free solder balls. Unfortunately, this lead to a problem of cracked solder joints that disconnect the solder ball from PCB boards and even pulling the pad from the PCB board. This led to many semiconductor companies replacing devices and initiating large studies to find the best solution. You can find many of this studies online:
This also led to life sustaining medical devices be exempt from lead free regulations to improve reliability. After all these studies, semiconductor companies figured out the best way to prevent this issue. This problem mostly affected early 2000 production devices.
AMD (who sold off their fabs in 2009) and Nvidia suffered through this much later than other companies. Both companies do not fabricate semiconductors. They contract the manufacturing to other companies. Since they are fab-less companies, they blamed their poorly selected manufacturing partners. So instead of replacing the parts, they have engaged in finger pointing and looking for someone to blame. Apple, Dell, Microsoft, and others electronics companies have been caught in the middle of this. Just much like the famous bulging capacitor issue...
Anyway, they all should acknowledge the well known problem and institute policies to fix it.
When my MacBooks fail, it is very random. So I just take a whole bunch of pictures of the failures and bring them to a Genius appointment. They will run their test and say everything passes, then I show my pictures. That usually gets the: "Oh that is really a problem!" One I forced a machine to fail at the store when I ran a game... Usually the pictures do a good job of explaining the problem. If I get a Genius saying this is new, I just pull up the link to the thread of this issue in Apple forums. That usually gets a quick, will send this off for repair...
Now be wary of 2011 used computers sold. They will eventually fail... Do not buy one if it has not have a motherboard replacement in the past year.