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I'd like to use a tri-color LED to replace my case's power LED. Ideally, it would be blue for on, red for off, and green for standby (S3).

Thing is, I'm stuck at building a circuit that determines if the computer is in standby. It's on when the motherboard header's power LED output is high (current present), and it's either off or standby when the output is low (current absent; the LED will be driven via the purple +5Vsb wire on the power supply).

Anyone know how I can determine between "off" and "standby" by probing connections on the motherboard, since the ATX power supply's control wires can't see the difference?

I know that in standby (S3) mode, there are more things powered up on the board than in "off" mode, which means that if I knew where to attach a wire, I'd know the difference. I'm familiar with the workings of an ATX power supply since I converted converting an ATX PSU to a benchtop PSU (adding a dual-color on/standby LED), but here it only mattered if the unit was on or not.

Thanks.
The Beast
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The Beast
(12 items)
 
  
CPUCPUMotherboardGraphics
Xeon x5670 Xeon X5670 Supermicro X8DT3-LN4F NVIDIA Quadro FX 580 
RAMHard DriveMonitorKeyboard
96GB DDR3 RDIMM Corsair Force GT HP LP2480zx Corsair K95 RGB with Brown switches 
PowerCaseMouseAudio
Corsair RM1000i Corsair Obsidian 750D Logitech MX1100 Creative X-Fi Platinum 
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