Is it safe long term to use a Jump start switch to power on the psu without connecting to motherboard?

[Masychefx2]

.

[_I_]

yes
as long as the psu is not plugged into the mobo
no 24pin and 8pin eps connectors

[Masychefx2]

just sata and molex power

[Viking2121]

You'll be fine, its the same thing as powering on the PSU with a case switch, its meant to be powered on by shorting the green to ground, it just normally done on the motherboard side.

I use to power a custom box I made for a garage stereo system, the box houses a sub and 8 inch speakers with a car radio and small amp, I powered it with a old Antec 600watt computer PSU and the switch was just shorting the green to ground to turn the PSU on, I built that in the Windows XP days, and I just recently gave it to my buddy as soundbars now are small and sound just as good these days, and blue tooth.

You'll be find in the long run, just don't short the wrong wires.