In this case, failing bit is bit 11 (0x800 in binary is 0b100000000000), so it is one of the 4 ICs with data bus bit 11, i.e. U2310, U2410, U2510 or U2610. In this picture, the channel is highlighted in blue ( MEM_* ), the CS# signal for the rank is highlighted in red ( MEM_*_CS_L<*> ), the bank select bits are highlighted in purple ( MEM_*_BA<*> ), the row/column address bits are highlighted in yellow ( MEM_*_A<*> ), and finally the data bus is highlighted in green ( MEM_*_DQ<*> ). We confirm that the memory IC is on channel A ( MEM_A_* , in blue), is selected by CS# signal bit 1 ( MEM_A_CS_L<1> , in red) and has data bit 11 ( MEM_A_DQ<11> , in green):