5160 motherboard slot restrictions?

[Michael B. Brutman]

 From the XT Technical Reference:

"Timing requirements on slot J8 are much stricter than those on slots J1 
through J7.  Slot J8 also requires the card to provide a signal 
designating when the card is selected."

Traditionally that slot was populated by the asynch card, which probably 
meets the requirements.  It's possible that your IDE card is either off 
on the timing or doesn't have the card select that the XT needs.