Not seen this before on my travels...
I have a Foxconn Winfast MCP61vm2ma-ers2h motherboard. It has 2gb of ram (2 Dimms, 1gb a piece), a 160GB seagate Barracuda and two SATA drives 400GB and 1.5TB).
I've just tried to add a 2GB dimm into the third bank. When I do, the POST fails to recognise the IDE hard disks anymore. The RAM is detected fine at POST.
and to get even more confusing, plugging in a standard DVD drive into the IDE channel and that works fine with or without the new 2GB Dimm.
I'm thinking BIOS on motherboard or Firmware on Harddisk....anybody have any thoughts?