Powering mini PC using ATX PSU with standby support
I have a mini PC that is powered using a 12V power brick using a DC barrel jack. I have 3 desktop HDDs connected to it (3.5 inch) which require a 12V power input and the brick that came with the PC is not sufficient to power them, so I am trying to repurpose an old ATX PSU for this.
I am aware I can short the PS_ON pin to ground and use the +12V to power the PC and the HDDs with the SATA power pins directly. But the PC isn't going to be running most of the times and be in standby (S3 state) instead. It will be woken up with wake-on-LAN when required and run for only 3-4 hours every week.
I need to replicate the behaviour of a desktop motherboard and keep the mini PC running using only the +5VSB output from the ATX PSU when the mini PC is in standby. How can I find the right point on its board to inject the +5VSB and the PS_ON to make the PC enable the high power 12V and 5V outputs only when it wakes up from standby? Is it safe to inject the +5VSB into the onboard SATA power output or into one of the USB ports and the 12V into the DC barrel jack?
The main purpose of not keeping the power supply running at all times is to prevent dust build-up due to its fan as the PC is in a dusty environment.
Alternatively, is there a simple way to build a slightly hacky solution to power the PC and the HDDs using separate PSUs and turn the ATX PSU on only when the PC is not in standby? Or is it a good idea to turn off the fan of the PSU when the PC is in standby mode?