Just installed a matrix infinity green dot into an SCPH-90001cb but it had this motherboard revision.
The infinity didn't work, took teh chip out, left the wires intact and installed a modbo 4.0 and it booted up. :crazy:
7900x and 90000x both need a 1k resistor between W on chip and GND to get it to work if your using Matrix Infinity (green dot) :) Sony did a litle change there so values are not the same as they where.
For 90000x you can use the modbo 745 install pics just remember the resistor.
and for 7900x http://psx-scene.com/forums/420752-post123.html allready reffered to in another post on this page. Also here remember the resistor!
Recently I have problem with 90002 GH-71-42 board.
I have installed Modbo4.0 in all other PS2's and so far so good until this model.
With the Modbo installed, the PS2 does not always boot. By boot i mean I don't see 'matrix' logo.
It works from cold start then about 10 min late, if you hit reset, the PS2 acts like no chip installed. If you try more rests , 2 out of 10 will boot. I have tried 1k resistor fix, and PNP transistor fix still same problem.
To me, it seems that the code for modbo4.0 needs to be fixed in order to fix this issue and I hope guys behind modbo4 are aware of this problem.
if that helps