Hard-Wire PSU on while Motherboard off?

I have a huge RAID in a PC case hooked to another computer and I'm thinking of throwing a motherboard/GPU/etc in there. The problem is I want the hard drives in the case to continue to receive power even when the motherboard is "off", or restarting or whatever.

Currently, I have the green wire hooked to a toggle switch and am good enough with soldering to keep it that way, even if the Motherboard Power Connector is in place.

My question is: Can I have this same setup and just add a motherboard, or does the motherboard need to have control over the relay in the PSU? Has anyone tried this?

I should clarify: currently the case contains a bunch of hard drives, a couple port multipliers, and a standard ATX PC PSU wired to a toggle switch

old pic:

Again, I'm just wondering if the motherboard will be upset if I keep the juice flowing regardless of if the motherboard turns "off"
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  1. You may have to do some customization of the BIOS; which is scary enough to start with! I do not recommend this.
  2. I haven't bought a motherboard yet. Any you can recommend which might have this function/be easy to modify? What happens if I just short out the green wire and keep power going regardless of what the relay on the mobo does? Will the motherboard restart itself every time it shuts off?
  3. The motherboard does not control the operation of the PSU. During startup of the computer the motherboard will sense the presence of the heatsink fan over the CPU and continue with the boot process.

    In the setup that you are considering, the motherboard will not be upset if you keep the juice flowing regardless of if the motherboard turns "off". Yes you can circumvent power shutdown by re-engineering the system. Presently, power is shut down to disk drives, optical drives, etc. when the motherboard is shut down because people do not want power to devices when the computer (motherboard) is OFF.

    An effective alternative would be to get another PSU dedicated to the new setup that you are considering. After all by adding a motherboard to the RAID enclosure you are effectively creating another computer. Why not let it have its own PSU? This setup will be easier to explain to others who may use the system at some date.
  4. Thank you so much! The case has room for only one PSU which is currently insufficient for the PC I want to build. I can easily detach the toggle switch, I'll just leave it in parallel with the 20 pin connector leads.
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