A mod for the EEPROM‐less AMD WX4170 cards
(content and post by @franetic)
Recently, @m0bil and I came up with a mod for the EEPROM-less AMD WX4170 cards to make them POST (and run) in iMac12,2 machines (2011 27' iMacs). (In all likelihood, they will also run in iMac11,1 and iMac11,3. They will not - see additional mod below.) It requires quite a bit more than 'above average' soldering skills, so I'll deliberately skip the details of the soldering process. (I did manage to do it with a soldering iron with a special 'drag soldering' tip, tweezers, a lot of flux and even more time and patience.)
(Original mod, next four photos) The 'missing' components - there are 4: top layer: 0R 0603 size SMD resistor (R1342, jumper) and P25Q40H (or equivalent) EEPROM (U10). (Make sure that the EEPROM is in the narrow - 150 mils - SO8 package.) bottom layer: 0R 1206 size SMD resistor (R2, jumper) and 4x 33R size 0804 resistor network (RP1). @m0bil was the one who traced the signal lines from the EEPROM to the missing RP1 resistor network. I simply added the two 0R resistors - similar to the WX4150 mod.
(Additional mod) To make the card work properly in 27' 2009-2010 iMacs (iMac11,1 and iMac11,3) removal of two additional 0402-sized 0R resistors (jumpers) is required. On the bottom layer, lower left corner, to the left of the heatsink mounting hole, there are those two jumpers in (again) orange rectangles. These two need to be removed. See next two photos:
