Power button will not shutdown PC outside of any OS (common issue I have)

[OgreVorbis]

This is becoming a recurring problem with many of the builds I've done and I want to know if anyone else experiences this and if there is a solution. . .

So pretty often I will be working on a system without an OS installed yet. Maybe I'm changing BIOS settings or running a Memtest for example.

Let's say I just finished the memtest, what happens is I'm only given an option to reboot, so I do so, even though I really want to shutdown. Once it reboots, I hold down the power button and it still just keeps rebooting. I try a short press, it reboots, long press, it reboots, super long press, reboot. ARRRRGGGGGG! So I just end up having to switch off the PSU and just kill the system. Why do I have to be mean to the mobo to get it to shut down? I did not change any of the power options in the BIOS. Why is the default to behave this way? If I'm in an OS, then long holding the button shuts down. This has happened to me on many mobos (although I think they were all ASUS boards if that matters). Anybody else experience this and know how to avoid it?

I'm sure it's not super bad or anything, but I don't like having to just cut power to the mobo.

[OhYou_]

is this a custom built pc? you probably plugged the power button cable into the pins labeled reset_sw
if not that then someting wrong with your case it is wired incorrectly. do you have both a reset switch and a power button on your case, what case is it