Z790-A WIFI D4 : FLBK LED blinks green continuously. No POST.

[Lena0309]

Hi there,

My setup :
ASUS ROG STRIX Z790-A GAMING WIFI D4 (BIOS 1801)
CPU : INTEL 13700K
RAM : Corsair Dominator Platinum RGB DDR4 64GB (4 x 16GB)
GPU : ASUS TUF GAMING Radeon RX 7900 XTX OC Edition
NVMe: Samsung 990 Pro MZ-V9P2T0BW
PSU : Corsair RM1000x 80 PLUS Gold 1000 Watts

The problem :
When I shutdown the motherboard, the BIOS FLBK LED starts blinking green continuously.
If I shutdown the PSU, then power it on, the BIOS FLBK LED starts blinking green again.
In this state if I try to power on the motherboard nothing happens : no fans running, no POST.
Now if I click the CLEAR CMOS button, the motherboard starts, do POST normaly (less then 30s) and enter BIOS. I set default parameters, reboot, windows 11 starts and all run fine, until I shundown the motherboard again.
Sometimes (seems random) when I power on the PSU the BIOS FLBK LED stays off. In this state when I power on the motherboard, it starts, but the POST is very long: around 2 - 3 minutes.

This situation is really weird !
I have tried the following few things to fix the problem but they did not help :

- Updated BIOS to 1801. I used the BIOS EZ-Flash tool for this purpose not the USB Bios flash port (nerver used it)
- Changed CMOS battery
- Used another PSU
- Started without USB devices (no keyboard, no mouse), and no dedicated GPU card

I sent a report to ASUS support but no answer yet.
Any idea, help ?

Thanks 🙂

[JohnAb]

That's an odd problem. Have a look at the BIOS flashback button and try pressing and releasing a few times with the power off. I'm wondering if the button is stuck down, perhaps just caught slightly on the motherboard shield? Or maybe the button is faulty? Only an idea. Maybe not a good idea because as far as I know, that LED should only flash if there is a USB stick in the port and it is being read. But you never know, perhaps a stuck button could give that effect. 

One other idea (but probably not likely) - could the case reset buttons or power buttons be stuck or faulty? Try disconnecting them and see if that helps. You can short the start pins with a screwdriver if the switch is disconnected. 

If that all seems to be OK, then I think I would try to flash the BIOS again. I have seen a couple of cases where flashing the BIOS again helped to resolve some issues. Try downloading the BIOS again and unpack it with WinRar, not the Windows tool. That has also helped others. Maybe the BIOS file was corrupted? Also unlikely as if corrupted it shouldn't even have updated the BIOS, I'm just suggesting what I might try. 

Also double check all cables, both at the motherboard and at the PSU if modular. Again, doesn't sound like a power issue, but no harm in checking. 

[Lena0309]

Hi JohnAb,

Thanks for your help 🙂

I have tried removing the connector from the system panel hearder and played with the power pins to start the mobo, but it did not help.
Same problems.

I had already tried to reset things with the BIOS flashback button. The button does not seem faulty. Pressed it during 3s whith PSU/On or PSU/Off, it did not help.

Concerning the BIOS: the problem started in version 1401. I upgraded two times to 1801, using the BIOS flash tool (EZ-flash whith BIOS image on NVMe). I dont think the BIOS itself is corrupted. But perphaps the data on the CMOS is. Bad information about BIOS flashing state could explain the flashback led blink ? Clearing the CMOS resolves the problem, but it comes again on the next power off.

I'm really thinking about replacing the motherboard.
However it seems that there is problems with Z690-Z790 motherboards, having abnormally long POST time.
I have read several topics about this problem. Really I dont think that this normal. POST time longer than 30s is probably a thing.
And in my case it can be even more than 1-2 min ! (whith BIOS defaults and no peripherals connected)
I Don't know which Z790 mobo I can choose, even the Maximus series seem to encounter long POST, and nobody seems to have any answer from ASUS on this topic.

[JohnAb]

Your comments make perfect sense to me and a shame that my suggestions didn't help. Perhaps you should try re-mounting the CPU before giving up, check for dirt debris and check the cooler mounting pressure. Otherwise, I agree that getting the motherboard replaced might be the next step. Why it works after a CMOS reset and then reverts to the same problem again is a mystery to me and also makes me think that it's probably nothing to do with the CPU at all. Remounting it is a long-shot, but you never know. 

As far as other motherboards go, I would say that the Apex boards seem excellent and I've very rarely seen any issues reported with those. Not cheap though, but if I had to get another, I'd go for an Apex but I'm holding out for Panther Lake Z990 in a couple of years. My 690 Hero has long POST times (nearly 30s) but that seems to be normal and it doesn't bother me at all. I must say it's been 100% for reliability and stability. However, I think that most boards are faster. Anything over 60s would not be normal in my opinion. Not sure what else I can say, hope somebody else here might have a suggestion for you, but I feel your pain! 

One more thought, have you carried out memory stability testing? Unstable memory can manifest itself in mysterious ways and memory training can lead to long POST times. You could try enabling fast boot in BIOS (can't remember if it's on or off by default) which means the BIOS will just use the last set of stable memory settings. 

Final suggestion - you said the problems started after BIOS 1401. Can you flash back to an earlier version and see if that fixes things...

[Lena0309]

Hi JohnAb,

I had already done full memTest of the DDR4 sticks. All was ok.

Now I think I'm done with the testing. I can be ok will long POST time, but not the motherboard not starting unless a CMOS CLEAR is done. I'm going to return the card to Amazon.

I will have a try with the Z790 APEX ENCORE and DDR5.
Hope I will get this one before the limit date for returning the Z790-A GAMING WIFI D4. If this is the case I will do some more testing when I will switch the motherboards. If something new I will give some more input here.

Thanks again for your help, it was great 🙂

[JohnAb]

Sounds good, just remember that the Apex Encore doesn't have Thunderbolt ports I don't think (please check) but otherwise they are great boards. The Apex will also give you fantastic RAM speeds 😃 Enjoy. 

[toshi-shigemi]

This case is Ader lake and Raputer lake Reflesh and of all main bords.  It doesn't Intel and ASUS's Warant . but This problem is Soket LGA1700 series Foxcon Edition