Question display no signal after Ryzen 5 2700x to Ryzen 7 3900x upgrade

Jun 29, 2019
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i just upgraded to a new cpu after and turned on the pc, everything works, all lights are on, all fans are spinning but the monitors don't turn on.
the old cpu does not work anymore so i cant put it back in.

Specs:
  • currently ryzen 9 3900x
  • rtx 2070 8gb
  • 16gb ram
  • gigabyte b450m ds3h am4 mATX
  • psu 750w
  • windows 10 professional64-bit
 
Jan 12, 2020
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Also worth a try doing a clear CMOS bios jumper reset (make sure you turn the system off an unplug the power cable first). I built a system that displays similar behaviour on a B450i mobo, everything working but no display, CMOS reset sorts it, it will POST and then you just reconfigure it (something weird with HDMI vs DP) - costs nothing to try this first!!

That said, as the others have already said, it's most likely with it being a 450 mobo that your mobo bios is not up to date enough for latest Ryzen. Some of the more expensive boards allow you to flash the bios without a chip in it (I got SCAN to update my board before they sent it out as I knew it was likely to be incompatible with 3400g). Here's a link to the explanation of your probable issue and AMD processor loaner programme:

https://www.amd.com/en/support/kb/faq/pa-100