CPU red light Motherboard

Associate
Joined
29 Sep 2020
Posts
12
Hi
Please help. I just make an upgrade with new CPU MB and RAM. The system work for 1 day and then suddenly went into black screen, refuse to boot with Red light CPU on MB.

Condition
- use it one day, play game, etc.. during a bios setting, the monitor just went blank and refuse to boot /reset/ turn off
- Blank screen, no post bios
- red CPU light on MB
- All fans working, other HDD seems to power
- refuse to power down with front on/off switch

CPU - 5800x (new)
MB - Gigabyte Aorus b550 Pro AC rev 1.1 (new)
RAM - 32 GB (16x2)Crucial Ballistix BL2K16G36C16U4R 3600 MHz, DDR4, DRAM (new)
HD - WD Blue SN550 1TB (new)

GFX 1070 Game rock Palit ( from old system)
PSU 550w Golden flower ( from old system)
Cooler Noctua U14s ( from old system)

Belows are what i tried

- unplug all usb cable/ other HDD from MB
- Reseat GFX, CPU, cooler, HD
- Reseat Ram and swap with 1 stick
- Flash/reflash new Bios to latest F13
- Reset CMOS and remove battery
- Reseat Mother board
- Swap Motherboard with another one similar model( i order 2nd one)

More checking
- CPU Pins are ok/ no bent
- MB 8 pins power (top of MB) - plug in
- reseat CPU cooler and try to boot without cooler with CPU fan plug in.

Could is be the CPU?

please help
 
Last edited:
Soldato
Joined
28 Aug 2017
Posts
2,755
Location
United Kingdom
check you havent overtightened the cpu cooler by mistake, as that can cause a red light to show on power up, failing that take the cpu out and check for any bent pins, if you find any try and straighten them but be super careful not to snap any of the pins or bend anymore, as above too make sure the 8pin eps cpu power cable is plugged in, if all of the above steps still give the same result then the cpu may be at fault, its rare but can happen
 
Associate
OP
Joined
29 Sep 2020
Posts
12
Is your 8 PIN CPU cable plugged in? And is it actually the CPU cable and not the PCIE 8 pin cable?

Yep the 8 pins are pluged and able to update bios without boot with Qflash

check you havent overtightened the cpu cooler by mistake, as that can cause a red light to show on power up, failing that take the cpu out and check for any bent pins, if you find any try and straighten them but be super careful not to snap any of the pins or bend anymore, as above too make sure the 8pin eps cpu power cable is plugged in, if all of the above steps still give the same result then the cpu may be at fault, its rare but can happen

- try CPU with no cooler on top with cpu fan plug in.
- to my 40s yr old eyes, no bent pins or any sign of physical damage. I really had to take photo and enlarge the pic.
 
Associate
OP
Joined
29 Sep 2020
Posts
12
Gentlemen... help please...

So, new CPU replaced by AMD, new PSU cosair rm850x, new GPU 3060ti

I test the CPU and things went fine during the test. Ran prime 95 for 1 hrs, ok during the test.

but when other things are fully assemble -- > CPU RED light again <--

Testing set up
  • MB inside case
  • Case open, Both side panels opens
  • 1 keyboard, 1 mouse
  • 1 NVME from previous installation
  • CPU Fan
  • Fan 1
Full set up
  • USB port to MB
  • Fan x 4
  • USB keyboard, Webcam, Mic, audio optical
  • Case both side panel close
  • 2 x HDD
Quick try
- reset bios

Theory (panic mode)
- one of the accessories short the circuit
- side pannel short circuit?
- one of the cables short circuit?
- Noctua u14s too close to case?
- some fan short circuit?
 
Last edited:
Soldato
Joined
28 Aug 2017
Posts
2,755
Location
United Kingdom
ah with regard to the boot issue again go through each component added in the full setup one by one and see where the pc stops working, when it does note down which component was connected and remove it and continue installing components, when you have everything plugged in you'll have your answer which component(s) is/are faulty.

when you plug the usb port in which one is it usb3, usb 3.1 type c or usb2, you have to be very careful with the type c as it only goes in one way or it'll cause a short and stop the pc from booting

Theory (panic mode)

- one of the accessories short the circuit (possible)
- side pannel short circuit? (very much doubt it)
- one of the cables short circuit? (possible)
- Noctua u14s too close to case? (if that was the case the fan would stop and pc would work normally)
- some fan short circuit? (possible but i suspect the pc woundn't power on at all to protect the motherboard)
 
Soldato
Joined
7 Dec 2010
Posts
8,222
Location
Leeds
Gentlemen... help please...

So, new CPU replaced by AMD, new PSU cosair rm850x, new GPU 3060ti

I test the CPU and things went fine during the test. Ran prime 95 for 1 hrs, ok during the test.

but when other things are fully assemble -- > CPU RED light again <--

Testing set up
  • MB inside case
  • Case open, Both side panels opens
  • 1 keyboard, 1 mouse
  • 1 NVME from previous installation
  • CPU Fan
  • Fan 1
Full set up
  • USB port to MB
  • Fan x 4
  • USB keyboard, Webcam, Mic, audio optical
  • Case both side panel close
  • 2 x HDD
Quick try
- reset bios

Theory (panic mode)
- one of the accessories short the circuit
- side pannel short circuit?
- one of the cables short circuit?
- Noctua u14s too close to case?
- some fan short circuit?


Have you updated the motherboard to the latest bios? Does the motherboard have a flashback button on the back and a USB port marked for bios flashing?

EDIT.. the motherboard has Qflash so update the BIOS with a USB stick and follow the instructions for how to Qflash correctly. You will probably need to rename the BIOS file.
 

V F

V F

Soldato
Joined
13 Aug 2003
Posts
21,184
Location
UK
check you havent overtightened the cpu cooler by mistake, as that can cause a red light to show on power up, failing that take the cpu out and check for any bent pins, if you find any try and straighten them but be super careful not to snap any of the pins or bend anymore, as above too make sure the 8pin eps cpu power cable is plugged in, if all of the above steps still give the same result then the cpu may be at fault, its rare but can happen

What kind of pressure does that require? thumbs or screwdriver?
 
Soldato
Joined
28 Aug 2017
Posts
2,755
Location
United Kingdom
What kind of pressure does that require? thumbs or screwdriver?

You want to aim screw tight but be careful not to over tighten, plus go corner to corner so there is even pressure applied when you feel the screes getting tighter or stop, that's when you stop don't keep putting pressure on as that will cause problems
 

V F

V F

Soldato
Joined
13 Aug 2003
Posts
21,184
Location
UK
Some heatsinks and AIO I've found they're tight on the first build then they bed in and slacken a bit requiring to be a smidge tighter. Some people must really ramp them in with brute force?
 
Associate
OP
Joined
29 Sep 2020
Posts
12
Have you updated the motherboard to the latest bios? Does the motherboard have a flashback button on the back and a USB port marked for bios flashing?

EDIT.. the motherboard has Qflash so update the BIOS with a USB stick and follow the instructions for how to Qflash correctly. You will probably need to rename the BIOS file.

Updated 23/9/21

Firstly, thank you all for the suggestions, this help a lot for a panic person.

I removed all UNimportant connections.
  • After few not boots, reseat GPU, reconnect all MB power cable, and reseting bios..... The system boot-up and able to ran Prime95 blend test for 1.5 hr.
Remove all connector from internal MB inc.
  • front audio, front USB, Back USB, all SATA
Still connect:
  • CPU fan, 2 x case fan, Keyboard, mouse, HMDI
I am now tring to connect each unimportant stuffs back and test to see if it boots, so far, all went ok.

Notice:
- Antec tri cool (with switch on Low) 10+ yrs fan does not operate, but when i change fan profile to full speed it does.


Have you updated the motherboard to the latest bios? Does the motherboard have a flashback button on the back and a USB port marked for bios flashing?

EDIT.. the motherboard has Qflash so update the BIOS with a USB stick and follow the instructions for how to Qflash correctly. You will probably need to rename the BIOS file.


MB bios is updated.

What kind of pressure does that require? thumbs or screwdriver?

I use screwdriver and only tighten it up to a point where i can not put excessive force to turn.
 
Associate
OP
Joined
29 Sep 2020
Posts
12
Hi

The CPU light on MB came up again. This time the system went into blank screen with only fans on during the screen saver mode.

The computer was working fine for few days, with prime95 test (60 mins blend) and gaming (1 hr).

Now i am disconnecting all fans (but cpu), reset bios etc.

Still refuse to boot and stuck on CPU red light
 
Associate
OP
Joined
29 Sep 2020
Posts
12
Just want to conclude the issue.
The red CPU light on MB is caused by some sort of fault or a compatiblity with other components(RAM). The issue seem to repeatly occur even when a new same model mother board is replaced. I think the Aorus B550 Pro AC is the cause of this issue.

Sadly, I now replace the board to MSI B550 Unify. I really like to quality and spec of the aorus.... :(
 
Back
Top Bottom