Ok, finally we are getting something thats not just theory.
Excellent.
I've got like forty thousand consoles and handhelds under my belt, several thousand reballs of various devices, maybe six or seven hundred backwards compatible PS3? I don't know, I been drinkin', and my memory ain't so good no more. Results are skewed from recency bias, but my guess these days is among 90nm RSX problems, it's a third BGA, a third bumps, and a third otherwise dead chip (electromigration or some random fluke). It's important to remember that bumps can accidentally (and reliably) be fixed when reballing. The success rate of my reballs is definitely up since I upped my limits on ohms testing.
So the current guess is that "when there are RSX related problems"...
(Worth remembering that this is only a subset of the 90nm machines that failed, and are no longer working. Many work, and not all of those that did fail, are related to RSX. I understand we are leaving out all the rest of possible problems that are nothing to do with RSX)
So when it is related to the RSX,
Roughly you expect it to be about
33% the big old BGA (reballing would legitimately work and solve the problem)
33% "the bumps" (reballing could "appear to work") (In theory, this is the 33% that the 65/40nm RSX fundamentally dont have. Thats it)
33% something else (reballing would simply not work) I guess it includes stuff like VRAM... Etc
If I am understanding it right,
Seems that the estimate changed slightly since last time, but still sounds reasonable to me. Now this raises some more questions:
How do each of those failures look like?
Are they the same or different symptoms, or slightly different behavior?
Most importantly I see you are making a distinction between "the bumps" and "something else". As if "the bumps" are something that you distinctivly recognize.
How?
As I understand it, In case of xbox 360 for example... the "broken bumps" can be identified because they can be "fixed" or temporarily reconnected by applying extreme pressure to the chips. The famous "bolt mods" and all that voodoo. (Notice I mean extreme pressure. Not really possible with hands or pushing, flexing etc.. Needs to be something like nuts and bolts)
Example: a 360 was successfully reballed but it just failed again with similar problem.
However, placing extreme pressure like a dodgy bolt mod, makes the thing work! It cant be the big old BGA because it was already reballed. So it must be the broken bumps. No longer in quotation marks. The chip needs to be replaced.
Now, do we see this in PS3? Notice how I am not trying to deny "bumpgate" or saying it cant be real in general or anything. Also I cant.
The only thing that I am asking is:
How does this translate to our PS3 in particular?
Because I dont think it is precisely the same. Thankfully we dont see PS3 bolt mods for example. But maybe is because they would not work? It would only work if the failure actually were "broken bumps".
So what is your way to know when you find that 33% of "broken bumps"?
Because I'm not so sure they are actually breaking... As some people mentioned before, often in the cases when there is the funny internal damage, it is an internal short between some of the data lines. Not really what you would expect from "broken bumps"... If anything, it kinda sounds like the opposite.
And thank you for the answer