At the last moment, the ASUS Z97-A MB fails to clear the post.
At the last moment, the ASUS Z97-A MB fails to clear the post.
This very old build has been trouble-free until about six months ago. It behaves oddly and inconsistently most of the time, though it usually works perfectly. Occasionally it enters a strange mode where I have to play an unknown song and dance for it to return to normal. Sometimes it’s fine for a whole month, then suddenly it stops working entirely. Previously, these issues would last only a day or two of random fixes, with no clear reason for recovery.
When the system is in this unusual state, three outcomes are possible: it may freeze on the “In search of Incredible” screen, it might proceed to the boot select screen before showing a black screen after pressing F1 and displaying all connected devices, or it could land on the BIOS screen, choose a boot drive, and then become stuck in an endless loop. The “BOOT_DEVICE_LED” will remain continuously red. The fourth scenario is rare but possible—it does work occasionally.
Every time this fourth state appears, it doesn’t follow any pattern or connection to the previous states. There’s no consistency.
I’ve tried all known fixes and combinations, such as:
- Removing or replacing the CMOS battery
- Reseating the CPU
- Disconnecting all peripherals
- Performing a power flush
- Removing the GPU
- Reseating RAM
- Disconnecting storage drives
The last option is intriguing because removing both storage devices still allows access to the boot select screen, which led me to believe they were the cause. But now it varies—sometimes it works on the ISOI screen, sometimes elsewhere. I’m exhausted from guessing and need clearer guidance. Could you suggest more targeted tests or solutions to help identify the issue more directly? Perhaps checking the PSU, testing the motherboard, or examining power cables would be useful?
What exactly does "power flush" mean? I've been doing this in various ways for about 35 years, and it's the first time I've encountered that term in any PC context. Have you actually swapped out the main storage device? Did you also reconnect any drives that were previously connected, or did you perform a clean install on the new drive and use only that one with no other drives attached? What is the precise model of your power supply, and how long has it been working? If it's as old as your motherboard, then it's likely just as outdated, along with the board itself—definitely a strong possibility. What happens if you leave all RAM except one stick in, and that stick is placed in the A2 slot (the second slot next to the CPU socket), with no storage device connected? And what about removing the graphics card using only the integrated graphics, keeping just one stick of memory and no storage, or just using the new drive if it exists? Sharing your complete hardware details would be really useful.
Power flushing is the method where the computer is disconnected from power, and the power button is pressed repeatedly to fully remove any remaining power. This ensures the system clears completely. What exactly do you mean by "Did I replace the primary storage"? You’re asking if you swapped out the drive and plugged in a known working one—no, that didn’t help because even with all drives unplugged, it still can’t reach the BIOS screen. That suggests the issue isn’t related to drivers. I tried your advice now, but nothing worked. Sorry for the oversight—I might have missed something important. If you think I forgot anything, just let me know and I’ll add it.
Certainly! Here is the rewritten version with the same structure and length:
Yeah, that isn't "power flushing". It's referred to as a "Hard reset". This is the correct method to follow when trying to fix recognition or hardware table issues with the BIOS, or after an update.
The BIOS Hard Reset process
Turn off the device, switch off the power supply unit and detach the PSU cable from either the wall outlet or the power supply itself.
Take out the CMOS battery on the motherboard for roughly three to five minutes. In certain situations, you might need to remove the graphics card to access the CMOS battery.
While the CMOS battery is removed, keep pressing the power button on the case continuously for 15-30 seconds, so any remaining charge in the CMOS circuit is drained. Once the five minutes are complete, put the CMOS battery back in, making sure to orient it correctly as it was removed.
If you had to take out the graphics card, you can reinstall it now, but be sure to reconnect any power cables and your display cable.
After that, reinsert the power supply cable, turn the PSU back on, and restart the system. It should show the POST screen and offer options to enter CMOS/BIOS setup.
Enter the BIOS setup program and adjust the boot settings for either the Windows boot manager or legacy systems, depending on where your operating system is installed.
Save your changes and exit. If the system successfully POSTs and boots, you can proceed further—this includes returning to the BIOS and configuring any additional custom settings such as Memory XMP, A-XMP, D.O.C.P profiles, fan profiles, or other specific configurations that may have been lost during the reset.
In some instances, after resetting the CMOS, it might be necessary to load the default or optimal values in the BIOS to properly reset the hardware tables within the boot manager.
It’s also important to note that if you encounter issues requiring a hard reset initially, checking for a faulty video signal is a wise step. Trying a different display—such as HDMI—can be helpful if there are no visual signals or error messages.
If a display is unavailable, switching to another monitor can also be beneficial.
Additionally, if your NEX650G PSU performed poorly even when new, given its age and warranty, it’s worth considering a replacement. Even if the problem isn’t with the PSU, replacing it could resolve the issue.
It would be wise to verify the BIOS version you have installed, as this is likely the cause of the problem.
It’s also good to remember that for any situation needing a hard reset, opting for HDMI or another display type can help if visual input is missing or non-functional.
Yes, I wasn't aware of the PSU I had inside. It seems quite old and weak. It's odd since I still have an 850W charger in my drawer. I'm not sure if it's dead or just dormant, but I'll make sure the 650W one is turned off.
I don’t have much information right now because I can't reach the F1 screen on the American Megatrends display. All I see is "ACPI BIOS Revision 2801." If that’s not what I need, then I’m stuck—I haven’t made it to the boot selection screen yet.
I never changed the OCd settings, so that’s fine. The pins are still in good condition on the motherboard, and the thermal paste is fresh. The only solution seems to be replacing the PSU. Should I run a test, like a pin check, to see if it works? I’m not sure if I should try to save this unit or just replace it.
So, your BIOS from 2015 might still work fine, and it shouldn't be connected to any issues. If it stabilizes, updating to BIOS version 3503 would be beneficial—it's three years newer and likely fixes bugs, adds support for newer hardware, and probably resolves some problems. But first, let's tackle one thing at a time; I'm sure the BIOS version isn't the main concern here.
What model is your 850W power supply unit? I can quickly tell you if it makes sense to try replacing it.
Yeah, if you have an RM850x and have no reason to believe there is something wrong with it, which, if there was, I can't see why you'd hold onto it, I'd at least give it a try. Maybe test it first to make sure it's ok if you have access to a volt meter or can go pick up a cheap one. You can get them really cheap at places like Harbor Freight or Walmart, or online.
https://www.harborfreight.com/elect...te...59434.html
https://www.amazon.com/LESEHIY-Digital-M...B0BMPBHBKV
You can use a paper clip to find out if it even turns on.
View: https://www.youtube.com/watch?v=ixcWCrYpw3Y
And with even a very basic volt meter you can test to see that it at least has basic functionality.
View: https://www.youtube.com/watch?v=ac7YMUcMjbw
I own a comparable backup PC. Gigabyte X97 gaming 7, 4970k, 1080ti. Newer 750w power supply. Constructed the machine in 2014. Upgraded the GPU to a 1080ti in 2017, which is excessive for the 4790k. The X97 1150 has been a dead end since 2015 with the introduction of the 1151 pin CPU's. I don’t have high hopes that it will run indefinitely. If you can’t get it working, test your power supply then the motherboard.