I'm building a PC using an Intel NUC motherboard and an external graphics card - both will run off 12V, but when the motherboard is in standby, the graphics card fan with run at full speed, as the 12V will always run to it as long as the power supply is connected to the mains.
Ideally I'd want a positive voltage from the motherboard (between 3-5V or so) sent to a circuit that will then relay the 12V to the graphics card when the motherboard is powered on. I know CMOS switches can perform similar tasks in low current scenarios, but the graphics card can pull 75W, so the current would be around 6.25A, far higher than anything I've seen. Any ideas on how to get around this? I think there might be a pre-built solution out there already specifically for small factor PC builds, but as I need to make a custom PCB for parts of it anyway, I'd rather just stick my in circuit on it as well.