Question ASUS Desktop powers on, then off, then on again, then Boot_Device_LED lit

[ambush]

My ASUS Z87-A based system has a weird problem: When I turn it on, it powers up for a couple of seconds, turns itself off, then it comes on again and stays on. Shortly after turning itself on, the red BOOT_DEVICE_LED is lit and stays lit. But it never enters POST, or at least no monitor shows a connection and the BIOS screen. There is no beep code.

Shortly before this happened, I inserted then later removed a Sound Blaster PCIe x1 card, which is probably the event that kicked this off, even if only as a result of nudging something on the mobo.

Here's what I've tried already:

1) Reset the CMOS -- No improvement.

2) Carefully inspected everything on the mobo and connected devices for visible shorts -- Nothing seen, but that certainly doesn't mean there are no hidden shorts -- No improvement.

3) Re-seated all components except CPU, including RAM -- No improvement.

4) Disconnected all secondary drives and peripherals -- No improvement.

5) Disconnected ALL USB and SATA cables, only built-in Intel and nVidia GTX 710 graphics cards present, each connected to a different monitor -- and when I say "all" I mean ALL, including every connector on the mobo, so this obviously means NO USB devices, keyboards, mice connected at all. (Of course the display card and build in graphics were left connected). -- No improvement; nothing showing on either monitor.

6) Left everything disconnected except the optical drive, with a bootable "live" DVD inserted so there would be something it could boot -- No improvement.

You see, I tried everything I could think of before turning to you hardware wizards for help. It might help if I knew what the red BOOT_DEVICE_LED exactly meant: NO boot device found? A boot device found but no bootable media found? The boot device is defective? (I've tried several boot devices, but the same symptoms remain).

What would you all suggest for the next troubleshooting steps? Surely the power-on, power-off, power-on issue is critical.

Thank you!

UPDATE: With only the optical SATA drive connected, I'm now getting a BIOS beep code of 1. It's an AMI BIOS, and their documentation says the following:

Boot Block Beep Codes
1 = No media present. (Insert diskette in floppy drive A)

UPDATE 2: Even with all the SATA drives and cables connected, I'm still getting a beep code of 1.

UPDATE 3: Once I reconnected all the USB cables and peripherals (keyboard, mouse, Bluetooth), the Beep Code went away. But all the other symptoms remain.

 

[panathas]

Are you sure that you managed to successfully clear the CMOS? Have you removed the battery? Also what PSU do you have? Have you tried testing with another PSU?

 

[ambush]

Are you sure that you managed to successfully clear the CMOS? Have you removed the battery? Also what PSU do you have? Have you tried testing with another PSU?

Thank you ENORMOUSLY for your response! I was worried my OP was too long.

Your hunch that I hadn't removed the battery as part of clearing the CMOS was correct. So I removed it, moved the pin jumper, and left the battery out for a good long while (with the machine unplugged, of course). When I re-inserted the battery and tried to power up, nothing happened at all.

I figured that the battery was dead, went out and bought a new one, inserted it -- and this time it at least powered up, but all the same symptoms remain.

I can't help thinking that if we knew what was causing the power on -> power off -> power on sequence, we'd know a great deal more about what could be wrong. don't you agree? Do you have any ideas about what's causing that?

Thanks again!

 

[ambush]

Oh, and about the PSU, I need to remove it to determine which one is in there (I have four other machines, so I'm unsure). And since I need to do that, I may as well try a different PSU while I'm in there. Fortunately, I have an unused one so I don't have to deal with the long, nasty job of stripping one out from another computer!

 

[ambush]

Well, the PSU that was in there is a Thermaltake ToughPower 750W Gold. The unused one is a Corsair 850W Gold. Unfortunately, while the main 24-pin modular cable was present, I apparently misplaced the 8-pin CPU power cable (I've heard that's kinda important )

I discovered that Amazon has a free next-day delivery on many products (maybe only for Prime members?), so I ordered a replacement 8-pin cable. I'll try installing the Corsair tomorrow.

 

[panathas]

OK try a different PSU and post the results. This issue points to a sort circuit somewhere or a motherboard (or BIOS) failure. I've also seen sorted graphics cards, RAM sticks, HDDs or even bad USB devices that can cause this system behaviour. Therefore you have to remove everything from the motherboard including the graphics card and test again. Finally you have to test each RAM module separately in each available motherboard RAM slot. I also would test without any RAM module installed, just to check the motherboard's behaviour. If nothing changes then I'm afraid that the motherboard is likely dead. Good luck.

 

[ambush]

Thank you once more!

The situation has gotten as bad as it can get. I received the cable I needed and performed a partial install of the spare Corsair 850 as planned. By "partial" I mean that I only connected the 24-pin ATX power connector and the 8-pin CPU power connector and nothing else. And I disconnected every peripheral, card, and cable and left only one stick of RAM in the only allowed configuration for just one DIMM.

But although the EPU LED lights up once the PSU is on (basically a "power applied" LED), pressing the power button did nothing whatsoever. I double-checked the connectors, but nothing helped.

I didn't mention it before, but I actually had a second unused PSU: A Corsair 750W 80 Gold. I should note that I no longer recall why these two PSUs were unused. I believe the Corsair 850 was left unused because I wanted to save a few bucks in my sky-high electric bill. I believe the Corsair 750 was unused because it is not at all modular, and only one of my desktops has enough room for the PCIe cables, all of which are superfluous, plus the case of this problem computer has all the modular cables already installed. BUT it's possible that both of them were left unused because they're both faulty. I imagine that paints me as stupid, but there you are...

Anyway, after the partial install of the Corsair 750, the same symptoms prevailed. It wouldn't turn on.

I agree that it's almost certain that the mobo went bad. Why simply installing and removing that SoundBlaster card caused this disaster is puzzling, but although I inspected the board very minutely for visible shorts, the most likely scenario is that swapping in/out the SoundBlaster card either caused a soldering point to break or caused a hidden short.

But I have a new question for you: Is it possible that more than just those two PSU cables must be connected to the mobo for it to turn on? It doesn't seem so to me, but this situation is so inexplicable that I'm just not sure.

Thanks for sticking with me!

 

[panathas]

In order to properly inspect the motherboard you have to also check its back side. Maybe the damage lies there and it's not visible when the motherboard is inside the case. Therefore you have to remove it from the chassis and take a look at that side and especially under the PCIe slot that you used for the Sound Blaster card.

No you don't need more than 2 power cables (ATX for the motherboard and EPS for the CPU). However there are some PC cases that have various controllers (fans, RGB etc) and may need an extra power connector. Also you have to make sure that the chassis power switch (and led) is properly connected to the motherboard. Additionally sometimes the PSU needs to be installed inside the case for the system to turn on. This is caused by bad case (or motherboard) grounding and the chassis needs to make contact with one of the PSU screws. This could also indicate a motherboard sort-circuit. So I think that you should try to properly install the PSU inside the case but you need to make sure that this specific power supply isn't faulty otherwise this test is meaningless.

How did you install/remove the sound card from the board? Did you properly ground yourself? Was the motherboard on or off? Have you turned the PSU switch off or unplugged the PSU power cable from the wall and pressed the case power switch one time to discharge the PSU capacitors? When the PC is off, the motherboard is still receiving power and when you need to install/remove a component (CPU, PCIe device,RAM) you have to completely cut off the power in order to avoid any possible sort-circuit. Additionally you have to ground yourself in order to avoid frying a component from ESD. Finally have you checked the PCIe slot (you used for the sound card) for bend pins, or any other visible damage? Good luck.