elbox sell atx to at adaptator with power circuit. you can put the cables from the power button of the tower on and switch on/off the amiga with the tower button.
as a user of a mediator 1200, I have no reset connector on pci bus or fast-ata. I use the reset connector on the main motherboard for resetting my amiga.
you can see picture of my french rewiew of dbox 1200 at:
one of the picture show the atx to at adaptator and an other one the reset on the main motherboard. sorry but french only. could more or less help you.
I have made a translation in english (not good) of the article but not used untill now. If you know a site for the same article in english, please contact me.