One of my 41's doesn't like modules in port 4

[Monte Dalrymple]

The card reader, unlike a regular module, is capable of driving the ISA line to wake up the processor. It sounds like the card reader ISA driver is always on. This is why the machine turns on when you plug in the card reader. It also explains the noise you are hearing - the card reader and the processor are fighting to drive the ISA line, putting strain on the switching power supply. It could be a short somewhere in the card reader, but more likely is that the controller chip in the card reader is bad.