Are you aware that the power switch on AT does exactly that? Yes, I mean the front switch, not the one on the back. It will completely cut mains power. So unless you mean ATX, I don't get your issue.There are times however that I need to completely power off a computer (either by unplugging PSU or flipping the power switch on a PSU that has on). Issue is that I have to move things around and then get my arm in behind the machines to do it. Is there an easier way I could do this where maybe I have a switch or something on each machine I could mount in front?
I have to pull the plug on my 486 every once in a while and hit the power button before plugging it back in for it to boot