Please don't think that everyone is wrong and you are magically right, only inexperienced starting engineers do that

and you can get a ban here for spreading misinformation. It is funny that new people thinking like you are still appearing sometimes, it looks like it will never end

~99% of popular nvidia chips fail inside them, the contact between the silicon crystal and chip base. Not the contacts between the mobo <> chip base. You can confirm it by applying mechanical pressure, almost NONE of the chips will react to it. While if it really were this particular problem, then it would react to pressure.
By doing reflow or reball process you are only temporarily restoring the contacts
inside the chip. The warranty return rate means nothing here, it is random, you have to stop making wrong conclusions, because you are fooling yourself also. You should know that a failing nvidia chip can be temporarily restored by the heating cycle (reflow ir reball) for a totally random time. Sometimes it works for a year. By doing reball instead of reflow it
usually works longer, because the chip gets 2x or more total heat amount/time. It is true that reballing makes the chip work for a longer time than a single reflow, but the same can be achieved by just heating it (or reflowing) 2x or more times. So by doing a reball here you are only stupidly wasting your solder balls, because the same result can be achieved by doing few more or longer reflows in a row. And neither of those procedures can be called a real repair, or a professional repair.
And even if we are talking about the 1% of the cases when the problem is between the mobo <> chip, it is best to replace the chip, as it will fail soon anyway because of it's age, 100% nvidia chips that belong to the
models that were manufactured using a faulty manufacturing process WILL fail. There is plenty of technical articles describing this problem.
http://www.theinquirer.net/inquirer/new ... -underfillhttp://www.theinquirer.net/inquirer/new ... 4-g86s-badhttp://www.theinquirer.net/inquirer/new ... -defectivehttp://www.theinquirer.net/inquirer/new ... a-55nm-badAnd don't you think that it's a little bit strange that only nvidia and ati chips react to reflow/reball and not the intel? Do you think the motherboard manufacturers are soldering intel chips differently? Time to use your head to make some logical conclusions, no? But you are also free to believe what you want...