I have 4 ps3s in total and they are all backwards compatible. Today I opened my 4th CECHA01 for maintenance and found that it has K4R271669H chips. I have serviced more than 10 CECHA model PS3s before and I have never seen a console with this RAM. I assume these are really rare. Also it was manufactured in May 2007. It may have something to do with the manufacturing dates.