Question ASUS Sabertooth Z77 No longer boots, VGA only light on


Aug 19, 2016
Anyone have old memory......

I have an old, old build of a Sabertooth Z77 board that sits in my closet and is a HyperV server plus security server. It's normally headless, and has been running fine for years that way.

Last night there was a power outage that looked lengthy, so I logged in (everything is on UPS) and did a shutdown -- naturally Windows had updates to process so it was a shutdown-and-update, but the UPS had plenty of power, the power light went off normally on the system so I assume it did and think that is irrelevant.

Later I powered off the UPS (to stop the beeping), and when power came back, powered it on, then powered on the system. Lights came on but... nothing.

Upon further investigation and putting a head back on it (Display port and USB Keyboard and mouse), it never boots. On the motherboard the standby LED is on but only one brightness (I have no recollection if it should be different, but the manual indicates two tones). No beeps. The only other light that remains on is on the empty PCI slot where a GPU might go. It hasn't had a GPU in it for years.

System disk is a SATA SSD but I do not think it even gets that far, there's also 2 other SSD's and about 5 HDD's in it, but again, didn't get to those.

So far I have:

  • Moved the jumper to clear CMOS - no impact
  • Found an old GTX640 GPU and put in the slot with DVI display - no impact (That GPU does not require separate power, and it used to work in that system some years ago when it was a desktop).
  • Checked all cables, notably checked the button speaker cable, no change.
  • When it reaches a steady state of not booted, if I press the reset button, there is a brief and minor increase in fan speed for maybe 3-5 seconds, then it returns to slow. The fans appear to be following previously programmed settings for relatively low speed.
I would not be surprised if the CMOS/RTC battery is dead, but even if so I would expect it to boot with the DP Monitor attached, or the GPU attached, at least to see something. The monitor never shows a signal at all. Is that correct, a dead CMOS battery should not stop at least reaching bios? Or should get somewhere that will at least beep?

That system is rebooted every few months for updates, but this is probably the first actual power cycle in about two years. But it was a clean power cycle, with a shutdown first, and switched off power from a UPS that was still charged. Power outage was community wide and not from storms (i.e. no lightning or anything similar).

I have read a lot of "VGA light on" postings but most are new builds.

Anyone have any old memory of the Z77 and have ideas what to try, other than "it's time"?