hardware PC Stuck in Boot Loop, Possible Power Supply Issue?

[thijsfranck]

Hello everyone,

 

Since last night, I've been having the following issue with my PC: it's stuck in a boot loop. When I turn on the PC, it seems to go through the POST, but then it crashes and restarts. On my screen, I briefly see the boot logo, but I can't get to Windows. Here's a video of the issue: https://imgur.com/dxsJ1gv

 

The last q-codes fluctuate between 99 and A0. A0 appears to be the final q-code during POST, after which the operating system would typically start up. Code 99 stands for 'Super IO Initialization', which might indicate that a component is possibly not correctly connected, or that insufficient power is being supplied to a component.

 

I've already tried the following:

1. Unplugging all peripherals. No change.

2. Disconnecting the GPU. No change.

3. Disconnecting all SSDs. No change.

4. Booting with only one RAM stick. No change.

5. Changing the RAM stick's channel. No change.

6. Trying a different RAM stick in one channel. No change.

7. Disconnecting the water pump and fans. No change.

8. Cleared CMOS. No change.

It seems like the issue lies with the power supply. I've noticed something interesting. My PSU has a self-test function. If I press the button and the LED turns green, everything is okay. If that's not the case, there might be a problem. Here's what I've observed:

1. When the PSU is completely disconnected from the system, the self-test passes.

2. When the 10-pin ATX cable is connected, the self-test fails. The other cables don't seem to be a problem since the light still turns green with them connected.

Here's a video of the self-test behavior: https://imgur.com/BTRDpRs

 

To be honest, I'm not entirely sure what could be wrong. Could there be a short circuit in my motherboard? Could the issue lie with the cable? Or is it perhaps time for a new PSU?

 

Specs:

Motherboard: ROG Maximus X Formula

PSU: Corsair AX1200i

OS: Windows 11 64-bit

 

Thanks in advance for all your help and suggestions!

[SpookyCitrus]

9 minutes ago, thijsfranck said:

When the 10-pin ATX cable is connected, the self-test fails. The other cables don't seem to be a problem since the

By this do you mean when the 24-pin ATX cable is connected? And by connected do you mean only when plugged into the motherboard itself or even just the cable not plugged into anything other than the PSU does it fail? If the PSU passes self test without the 24-pin ATX cable plugged into the PSU, but fails when it is that could mean it's a bad cable. However, if it passes selftest with the cable plugged in but not connected to the motherboard and then fails when connected only to the motherboard that would mean it's most likely the board itself.

 

Can you please clarify, not only the cable but the specifics behind when it fails please?

[thijsfranck]

20 minutes ago, SpookyCitrus said:

By this do you mean when the 24-pin ATX cable is connected? And by connected do you mean only when plugged into the motherboard itself or even just the cable not plugged into anything other than the PSU does it fail? If the PSU passes self test without the 24-pin ATX cable plugged into the PSU, but fails when it is that could mean it's a bad cable. However, if it passes selftest with the cable plugged in but not connected to the motherboard and then fails when connected only to the motherboard that would mean it's most likely the board itself.

 

Can you please clarify, not only the cable but the specifics behind when it fails please?

Regarding the 24-pin ATX cable, it separates into a 10-pin and a 14-pin connector on the PSU end. Additionally, this same cable branches into the 8-pin motherboard connector. It appears that the 10-pin connection on the PSU side is causing the self-test to fail when it's plugged in.

 

Here's what I just tried:

1. With the 24-pin and 8-pin connectors plugged into the motherboard, and the 10-pin plugged into the PSU, the self-test fails (the LED doesn't light up).

2. With the 24-pin and 8-pin disconnected from the motherboard, but with the 10-pin still plugged into the PSU, the self-test again fails (the LED doesn't light up).

3. With the 24-pin and 8-pin disconnected from the motherboard, and the 10-pin disconnected from the PSU, the self-test is successful (the LED lights up green).

Given your suggestion, it appears these tests single out the cable as a probable cause. Would this be correct?

[Whatisthis]

Yes, if plugging in the 10 pin into the psu makes it fail, it seems like the cable is the culprit.

 

A final combo I didn’t see you try is plugging the 24 and 8 into the motherboard and just leave the 10 pin off the psu side. It should pass. 

[thijsfranck]

16 minutes ago, Whatisthis said:

Yes, if plugging in the 10 pin into the psu makes it fail, it seems like the cable is the culprit.

 

A final combo I didn’t see you try is plugging the 24 and 8 into the motherboard and just leave the 10 pin off the psu side. It should pass. 

You're right, good catch! I tried the self-test with this combo and the LED lights up green as expected.

I'll order a replacement cable and report back if this solved my problem. Thanks for your help everyone!

[thijsfranck]

Unfortunately, replacing the cable did not do the trick, and the same problem still persists.

 

I have recently replaced the cooling paste on my CPU and GPU. While the system has run fine for a while since, maybe I made a mistake in reassembly?

 

I have already reseated the CPU yesterday evening, but this did not solve the problem either. Will try taking the GPU apart again over the weekend to see if I can find any issues there.

 

Any other ideas?

[UnusualDevices]

so you cannot post to bios?

and you tried with nothing but cpu and ram and still couldn't post to bios?

 

[thijsfranck]

Yes, correct.

 

I got a tip to check the status leds on my motherboard in addition to the q-codes. I will do this later today to see if these will tell me anything.

[thijsfranck]

Here's a video of the status LEDs on the motherboard: https://imgur.com/a/ELfQj3M

 

The LEDs go as follows: CPU -> DRAM -> VGA -> BOOT. They light up one by one until the BOOT LED turns green. After that, the PC turns off and the boot loop restarts.

 

From the manual:

Quote

Q LEDs (BOOT_DEVICE_LED, VGA_LED, DRAM_LED, CPU_LED)

Q LEDs check key components (CPU, DRAM, VGA card, and booting devices) in sequence during motherboard booting process. If an error is found, the corresponding LED remains lit until the problem is solved.

 

Not a very useful description, but it does seem that the CPU, RAM, and GPU pass the POST successfully.

 

Having tried booting with all other components disconnected, and given that the loop continues to occur, does this isolate the PSU as the probable cause of the issue?

[thijsfranck]

I have replaced my PSU and this has solved my problem. Thanks for the help everyone!