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Journeyman III

3900x wont post

Upgrading to a 3900x 

R9 3900x

Tuf gaming b450 plus mobo

Corsair vengeance pro rgb 8gb 3200mhz

Cr550watt bronze psu

Gtx 1050ti gpu

I upgraded to the latest bios using a 2700x but soon as the 3900 goes in the fan spins for a second and stops all rgb's light up fans spin but no display output i have tried clearing cmos and I know all items work except the 3900 as thats not lol could I not have enough power and need a bigger psu? Or is my cpu dead

5 Replies
Adept II

Re: 3900x wont post

I hope you didn't get the failure as I got in my 3900x when it was first released, but try these before:


Disconnect the power cable

Check whether you installed the processor, thermal past and the heatsink correctly. 

If you can get a mobo small speaker to connect it would be good idea to give post/error beeps. 

Ram should be installed in gray ports 2-4 and re-install them. 

Hold the power switch for 30 sec while the power cable disconnected. 

Connect power and check.


Tags (1)
Adept II

Re: 3900x wont post

If possible - to test the PSU, find a less power-hungry/cheaper PCIe graphics card. Remove all other components, including the HD/SSD, not required to POST. See if the box POSTs with a low(er) current draw.  

Ryzen 5 Pro 4650g, ASRock B550 Phantom Gaming 4/ac, 16GB Crucial Ballistix 3600MHz, SAMSUNG 970 EVO NVMe 500GB, Super Flower Leadex III Gold 850W, Linux Debian Bullseye

Re: 3900x wont post

First lets go for the obvious...

You didn't by chance plug the video output cord into a port emanating from the I/O shield?

Sometimes graphics card are not inserted fully, or maybe the back is down but the front up.  (I suggest re-inserting)

Make sure the PCI-E cables are not just attached but fully seated.

Your monitor is powered  on.

If your monitor takes multiple inputs (HDMI, DP, DVI) the proper input is selected from the monitor.

Unplug the monitor, and then replug it in.   My monitor flashes the vendor name.  This can help you figure out if the monitor is dark, or if it isn't getting a signal from down the cable.

You mentioned that your fans spun for a second.  Was this just the fans spinning or revving up?

Fans revving up to full speed indicate that they are being tested by the BIOS, which would indicate your CPU is functioning.

The system doesn't know how fast your fans are, so they blast them full speed at Post.  They make note of their 100% speed, and if you request them to run at 30% later, the system will know how fast to drive them.

My hunch is that you are not getting a signal from the Video card to the monitor.  That's the first place I would look.


Re: 3900x wont post

When you boot up with the 3900X you said the CPU fan runs for a second and stops. What Motherboard Trouble LED is lit up when this happens?

So basically what you are saying that no motherboard fans like the computer case and CPU fans are running when you boot up correct?  So the computer shuts off power when it tries to boot up.

Is it the CPU Trouble LED or the RAM Trouble LED?

It probably isn't your PSU since the GTX1050ti only needs a PSU of 300 watts to run the system and during boot up your processor is not running at its maximum wattage so it should boot up.

One way very good way, if possible, to test your 3900X is by installing it in another compatible Motherboard and see if the same thing occur or not.

But first post any Motherboard Trouble LED lights that are lit after applying power to the Motherboard and any Q-Codes  if applicable.  Or what Beeps sequence sounds when booting up. This will narrow down which hardware is having issues.




Journeyman III

Re: 3900x wont post

Isn’t failures like these usually a driver problem with the operating system? I just repeatedly patched mine until it worked because my wifi is so slow that it won’t update properly.