Question 2 year old system - B450 Tomahawk Max red CPU light plus black screen

Nov 21, 2021
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MSI B450 TOMAHAWK MAX
AMD RYZEN 5 3600

I've been using this system for two years with basically no problems, and no recent hardware changes, but last weekend I started getting occasional random reboots which got worse and worse over the course of the next few days. Eventually, yesterday morning, I turned it on and saw my desktop one last time, for just a few seconds, and then everything went black (with the red CPU light shining). Then I removed and cleaned the CPU and CPU fan, applied some brand new Arctic Gorilla, and reinstalled the CPU + fan. I saw a few lines of text then so the monitor is working (it was saying something about a new CPU being installed and should it enter setup or apply defaults, I chose the latter). Checked the power connections, reseated the RAM modules and flashed the BIOS. No diffetence. Still no post screen. Last night I spent 240 dollars on a new Ryzen 5 3600, I installed it this afternoon, and it made no difference! Still no POST screen! Not even "new CPU" text. Nothing... except that steady red CPU light.

So do I now need to get a new MOBO?
 
Nov 21, 2021
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I did buy that PSU some time ago - maybe ten years ago - but it was shrinkwrapped until this past July. The previous PSU smoked and this Corsair was in my closet. Ran flawlessly
 
Nov 21, 2021
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I should have mentioned before, that while the power button will turn the PC on, if I depress the power button for 5 seconds, it has no effect. The only way to turn it off is with the PSU's rocker switch. Does this indicate a problem with the MOBO?
 
Not necessarily.
Depends on the power option set in the bios and windows.
Do you have a multi meter and know how to use it?
Test the output of the 12v atx/eps( 4/8 pin cpu power wire) connector to see if it has 12v.
Don't get me wrong it was and could still be a great power supply, but electrolytic capacitors age and dry out over time. Whether in use or sitting on a shelf.
 
Nov 21, 2021
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Installed a new EVGA G3 650 last night and unfortunately nothing changed. I will try replacing the MOBO tonight. Maybe it was damaged back in July when my previous PSU smoked. Went snap crackle and pop, it did, and filled the apartment with acrid smoke. But that was four months ago and my rebooting problems only started a week ago, and it was only on Saturday that my PC died...
 
Nov 21, 2021
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I can't believe it.

I replaced the PSU with an EVGA G3 650. I replaced the B450 Tomahawk Max with a new B450 Tomahawk Max II. I replaced the old Ryzen 5 3600 with a new Ryzen 5 3600.
Nothing has changed. Still a black screen, no POST, and the same sinister red CPU light.

I've replaced everything except for the case, the SSD, the memory modules and the video card. I'm at my wit's end.

I'm starting to wonder if the problem is evil spirits.
 
Nov 21, 2021
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So tonight I plugged in the little motherboard speaker (I know, it should have been there ages ago), and I removed the ancient sound card and the RX 580, and plugged the monitor into the motherboard's HDMI port.

Still nothing but a black screen.

Beeps: 1 long, 2 short (video card memory issue?) And now the VGA light is lit!

Also, for the first time in a week, the Power button on the front panel works!

Standard fiddling with memory modules had no effect.

NEXT I took a very old video card - known good, it is from a working Linux box - a Sapphire Radeon HD 5770 Vapor-X 1 GB - and plugged that in.

Still just a black screen.

Beeps: 3 long (?)

And now the DRAM light is lit!

And now the front panel power button doesn't work anymore! Well, it kind of does, but you have to lean on it for 5+ seconds. It wasn't even doing that yesterday.

Does any of this make sense to anyone? Please help! I'm at a loss!
 

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