Question ASUS Z87-A htpc will not respond to power/reset buttons - green blinking led

Apr 15, 2020
I have an older HTPC built from spare parts:
ASUS Z87-A Motherboard
Antec 640w PSU
Intel i7 4770k
Some g.skill 8gb ram
An SSD for windows 10
HDDs for video recordings
An Avermedia OTA HD PCIe card

Its been running fine for years. Today we had a power out, and my APC UPS kept it going for as long as it could (I was away), and its plugged in via USB, so I can only guess the APC told windows 10 to shut down or not, and it just cut power. Either the way it went, the whole HTPC will not boot now.

  • I tried the normal power button, held the power button for a bit too.
  • The reset button, held the reset button as well.
  • Power off the PSU with the hard switch, and back on.
  • Changed the lil battery.
  • Unplugged everything except the CPU (since its pretty stuck on and I dont want to redo the HSF and AS5).
All it does (when I turn the PSU power switch on), is blink this big fat green LED that is near the lower corner where the front-panel connectors are. I looked in my manual, and there is no diagram pointing to this LED, nor any specific information about it, or what a blinking green led means. The computer simply does not start up. No beeps, no "red" leds, no spinning drives, the fans don't budge... nothing!

At a loss here.

Question: Any ideas what I could try, or what it is?
Apr 15, 2020
After some fiddling about, and finding no answers about this motherboard's odd green LED (not in manual), let alone what a blinking one meant... I tried changing the PSU out. I had a spare 750w Corsair, so I rigged it in to the board plugs, just to see what would happen.

The computer started right up. >_<

So, I pulled the Antec 650w out, and rewired the whole thing with the Corsair 750w, and it seems happy and working again. The 650w was oversized as is, but now the 750w is way over sized, but it wont harm anything.

Would have saved me a lot of headache wondering what the problem was had the motherboard mfg added that tiny bit of extremely useful information in their manual (even under the general troubleshooting area or something): A Green Blinking LED means power source is faulty [or something].

I'm guessing that the 13 yo Antec PSU, finally fell out of spec during that 3 hour power out (it HAD been running 24/7 for 10 years).... it had 'rested' too long and just couldn't get up the oompf to supply the kind of power the board was expecting, and it just all came to a halt.