Question Red CPU debug light on new build motherboard.

Jan 26, 2022
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I have recently built a new PC.

Specs:
Intel i5-12600k
RTX 3080ti
Z690 Aorus Elite DDR4
Vengeance LPX 16gb ddr4 RAM
Corsair RM750 PSU
Noctua NH-U9S chromax black

When turning the PC on the red CPU debug light flashes on the motherboard along with the DRAM red light and there is no output to the motherboard. The monitor is connected via a DisplayPort cable to the motherboard. All fans are working.

Initially I believed it was an issue with the motherboard, so I replaced the MSI Pro z690-a with the new motherboard listed above. Same issue. I then replaced the cpu for a new 12600k, same issue.

All parts are brand new and never used before.

I have browsed forums and tried all possible fixes,
  • try with one stick of RAM, moving the RAM etc
  • replaced motherboard
  • replace cpu
  • boot without gpu
Nothing seems to be working and I am very confused. I have plugged in all power cables according to MoBo manual and the RAM is in the correct slots.
 
Jan 26, 2022
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RAM LED is solid or blinking? It it's solid then your first thought should be dead RAM. Did you test each stick alone?
Hi,

Both lights blink, it blinks red CPU then RAM, then back and forth continuously.

Yes I tried with 1 stick of RAM using each stick, changed the channels and so on, but no luck.
 
Jan 26, 2022
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Did you connect the CPU power to the top right of the motherboard?

Try removing the GPU entirely.
Hi, thanks for the reply.

Yes my motherboard comes with a 8x4 cpu port connectors, I have tried connecting 8x4 and just the 8 pin, neither fixed the issue.

I have also tried without the GPU altogether and it did not fix the issue.
 
Jan 26, 2022
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I see CMK16GX4M2B3600C18R ver4.31 on the QVL. Is that what you have? Is it 1.35v? The timings should be 18-19-19-39. You did buy the RAM as a kit of 2 sticks, correct?
Hi,

I definitely have the CMK16GX4M2B3600C18, not the ones ending with R.

Yes I bought the pack as a pack of 2 sticks? 8gb each.

Unfortunately I don't have a way to test the RAM on another PC. Is it possible the RAM caused the red CPU light to flash.
 
Hi,

I definitely have the CMK16GX4M2B3600C18, not the ones ending with R.

Yes I bought the pack as a pack of 2 sticks? 8gb each.

Unfortunately I don't have a way to test the RAM on another PC. Is it possible the RAM caused the red CPU light to flash.
I assume you can't get into the BIOS, correct? If you can't get into the BIOS, I don't think you can run Memtest86 from a USB stick either.

It appears that either your RAM sticks are bad or not compatible with your motherboard, but you don't have a way forward to figure out which it is. I assume you've checked (and rechecked) you're fully inserting the RAM stick(s). Is it too late to exchange the RAM with the vendor?
 
Jan 26, 2022
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I assume you can't get into the BIOS, correct? If you can't get into the BIOS, I don't think you can run Memtest86 from a USB stick either.

It appears that either your RAM sticks are bad or not compatible with your motherboard, but you don't have a way forward to figure out which it is. I assume you've checked (and rechecked) you're fully inserting the RAM stick(s). Is it too late to exchange the RAM with the vendor?
Hi, thanks for your reply.

After leaving it for a long time and completely rebuilding it, it turns out that one of the RAM sticks is defective. The PC works when one specific RAM stick is in one specific slot.
 
Jan 26, 2022
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Thanks to everyone who helped out, this really is an incredible community.

The issue turned out to be with one of the RAM sticks. After trying each RAM stick in each separate slot, it turns on when one specific RAM stick is in one specific slot.

Thank you all.
 
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