1st of them misbehaved and froze when AnTuTu Benchmark was started. I thought I just got unlucky and thought about software/firmware issues.
Today tried the other one and it was fine - no problem.
Started looking into the kernel numbers, read some of your forums... But it did not make 100% sense what I was reading, so I finally decided to open it up: used very fine blade knife first to pry it up from the corner far from the volume control and then inserted old credit card to keep it on till the other side - carefully for not to crack the plastic or not to scratch.
Here is what I found (1st image):
Then I just could not understand: people are saying old PCB has problems, as the flash fixes problems for new PCB... But mine is new PCB... Then people were running at lowest speed with old firmware while others had crashes or touchscreen not working...
So I decided to open up the one that was working (second image):
And surprise surprise I HAVE THE DIAGNOSIS!
Does anyone of you see the difference yet?!
To confirm my suspicions I have opened up all of them and it was confirmed (3rd image):
Now the PROBLEM of all the freezes and touchscreen stopping working is very easy - HEAT, and in that particular case is OVERHEATING.
If you notice the PCB by itself is the same, there are the same elements and chips on the board, but the difference is that the tablets built after 30-08-2012 all of them would have the miniheatsink from the metal, than you could see soldered and with thermal pad between it and the CPU + GPU, then plus metal pads for it to touch that fine aluminum backpanel to get the heat off the chips. That is what the previous builds are lacking - no proper heat-sink, just thermal pad and then no proper contact with the back panel.
Believe me the chip gets HOT just a moment you start running a benchmark and obviously it crashes as it overheats.
If you what experimental data - just touch on the heatsink over it when running benchmark - at the end you would like to keep the finger away and not get burned :-D
SUGGESTION: if you have a problem so then open-up your tablet and prepare to fill that space between the chip and the back panel with extra thermal pads and metal meshes.
I will keep you informed later and probably after X-mas when I would get those materials and try to fix it.
And here you may look at other photos and see that all of them have NEW PCBs and different versions of them. there is only one of them with different build and there is only one of them that crashes.
Feedback would be very appreciated!! :-D