Here are images of A5X Max.
It really has 4GB RAM (8x512MB chips, 4 on both sides).
I have been unable to boot anything from SD card.
No obvious place to solder serial console either, or at least I can not see it.
I would like to run linux on it. I kind of hoped I can when I picked up really good deal and was really excited about 4GB RAM. But so far no progress.