B550 Tomahawk won't turn on anymore

[Dalsecco]

Hi all. Almost a month ago I built a PC with a B550 Tomahawk and a 5600X, updated the BIOS trough "BIOS Flashback" (vA7, since vA8 was still in beta) before installing the CPU and everything worked fine until last week. Tried to power up the PC and nothing happened (no signals of power). First thing I'd think of was a defective PSU, which I exchanged for something else I had and still didnt manage to make it work. I tried to do a BIOS flashback again (using the latest BIOS version available - vA8) and surprisingly it worked and also restored my PC to life.
Two days later, PC wasn't turning on once again. I tried another BIOS flashback (this time the red light blinks, then turns off and nothing happens), as well as removing the battery and clearing CMOS. I feel like there's nothing else I can do other than sending it to RMA, which makes me really disapointed. I'd be really really glad if anyone is able to guide me trough some other type of troubleshooting.

Here's some of my PC specs if necessary:

MSI B550 Tomahawk
Ryzen 5 5600X
XPG Spectrix D45G 16GB (2x8GB) 3600MHz

Thanks in advance.

 

[Alan J T]

Have you tried it out of the case and by jumping the Power on pins

Could be just bad Cables on switch in the case


>>Posting Guide<<

 

[Dalsecco]

Hmm... I haven't tried to jump the power on pins. How exactly should I do that?
Also, it didn't let me downgrade the BIOS, isn't this kinda weird? I tried to go back to vA7 using BIOS flashback and the board wouldn't even turn on.

Thanks for the answer, btw.

 

[citay]

What are your two PSUs and how old are they?

Do you have a reset switch on your case? If yes, you can put the cable of the reset switch onto the pins for the power switch, and try to power on your PC by pressing reset. This will exclude your power switch as the culprit (they can start to malfunction).

 

[Dalsecco]

Both PSUs are "XPG Core Reactor 650W (80 Plus Gold)", the one I'm using in this PC is a month ish old, the other one is close to one year old.

As per the reset switch, I do have one on the case and have tried that, still didn't work. So case is perfectly fine, I guess.

 

[citay]

Hmm ok, that PSU model is a good one. There's still a slight question mark because they're two identical ones, so it would be good to get a true "second opinion" with a different PSU. But they're not the main suspects i think.

Reseat the graphics card and unplug (SATA) or remove (M.2) all drives, see if it starts then. If not, try with only one RAM module in the second slot from the left (A2). You can also try taking the board out of the case and putting it on a wooden table or non-conductive surface. Perhaps there is some kind of short with the case.

 

[Dalsecco]

Unfortunately I don't have any other PSUs, nor do I know anyone who has one, but ye I excluded the PSU as the main suspect.

I removed the GPU everytime I'd try to start the PC up, as well as removed all drives and got nothing to work. Also tried the one RAM module method but it did not show results.

I give up, guess RMA is the way now...

 

[citay]

Did you try it with the board out of the case? Tried another power outlet on the wall?

 

[Dalsecco]

Tried on three different power outlets, no issue with them. All tests I did were pretty much with the mobo out of the case.

 

[citay]

When you tried the BIOS Flashback the third time, did you use the same USB stick prepared the same way? Can you still make the LED blink by trying it now?

It confuses me that you could resurrect it once with that USB Flashback function. Normally, when you have a hardware issue, a function like that won't cure it. So it might be a weird BIOS issue, maybe combined with a hardware issue? Really odd one.

 

[Dalsecco]

I used the same USB stick but formatted it multiple times before downloading other BIOSes. Everytime I press the BIOS flashback button, the LED blinks a few times and then it stops but the board doesn't turn on.

I'm also extremely confused on how I managed to bring it back to life, since not even clearing the CMOS was helping in any way. Could my B550 be bricked or something now?

 

[citay]

I can't tell you that with certainty. Are any of the EZ Debug LEDs ever on when you try to boot? Can you test with everything removed, including the CPU, GPU, RAM, drives? Then at least the EZ Debug LEDs should complain. And then test again with your CPU.

If there are no EZ Debug LEDs on with any boot attempt, then it's between the board and the PSU, with the board obviously being more likely.

 

[Dalsecco]

None of the EZ Debug LEDs turned on, it was like the mobo was dead. Interestingly enough though, when I brought the board back to life, the CPU debug LED stayed on for a few secs, then disappeared (took more than the usual, from what I saw). I'll test the board without anything on it after lunch and see what happens.

Little noob question: can I just sit the cooler on top of the CPU without any thermal paste just to test if the boards turns on? ofc with the fan conected to the CPU_FAN header.

 

[Dalsecco]

oh also, how do I jump the power on pins? like Alan told me to.

 

[citay]

Yeah you can do it without thermal paste for testing, however, fasten the CPU cooler properly. It exerts a certain mounting pressure which can be necessary.

For the power switch, as i said, just put the reset switch cable on the power switch pins, then the reset switch will work as the power switch. Or you can try shorting the pins with a screwdriver.

 

[Dalsecco]

Aight. So little update: I did what you told me to do, Mobo turned on both with power and reset buttons from case (only mobo without anything on it). Now I’m gonna try with the CPU on and see, if it still works I’m gonna put CPU + RAM.
And thank you for making the cooler thing clear for me.

 

[Dalsecco]

Mobo + CPU not working, I suppose I’m the lucky one to have a defective CPU?

 

[citay]

So the CPU blocks the board from starting, eh? What happens with the CPU in there, but no RAM?

 

[Dalsecco]

Correct, CPU is blocking the mobo. CPU in there but no RAM is the same, mobo just won't work.

 

[citay]

So it's still not 100%, board or CPU. They perform an intricate little dance to boot. Normally, on Intel i would say, no way that the CPU has a problem, it must be the board. But on AMD, i actually saw people swap their CPU and everything worked again. Somehow the CPUs seem more prone to failure or problems than on Intel. And it sure looks like the CPU is causing the issue now.

Ideal would be to test a different CPU in your board. Any of the supported CPUs, can be the cheapest one. This is the only way to tell for sure.
Otherwise you have to gamble and hope you replace the right part.