There has been some unexplained errors on 4100’s models after HD’s were upgraded. Further investigations show that a modification/repair was made to the original MB, ASSY# 707150048-001. The area of repair/modification was made to 2 areas FB1 & FB2.
FB1 is located between the two Promise Controller. The second area FB2 that has the same repair left of the left promise chip. This one (FB2) points toward the IDE cables.
If you have a ASSY # 70715048-001 or 003 look at the photos below and see if you are affected. 003 seams to be the repaired boards. But so far I have found 1 (-003) that has not been repaired. So you will have to look on the board for the repairs. Now some of the repairs have been done differently than the photo posted. If you are not sure post a photo of the area in question.
This is a -001 board that has NOT been repaired.
This is the 003 board showing locations of both area.
Below are pictures of a 003 A board that has been repaired.
FB1 area.
FB2 area
Notice that 1 component has been replaced with 2 and are bridged together with solder.
For more info please post your questions.