Taichi x470 + 5800X - boots but no video

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   Hi guys,

I have a Taichi x470 motherboard, and I recently upgraded my CPU from a 2700X to a 5800X.  I flashed the BIOS to 4.70 before I did it, and reset the CMOS.  It boots no problem, and I can hear the Windows startup sounds and things, but there's no video signal, not even the BIOS boot screen.  The monitor stays completely asleep.  I tried downgrading to 4.60, and the same thing.  I can swap in the 2700X and there's no problem, it boots perfectly with video.  But if I put the 5800X in, while it will boot Windows, I can't get the video card to be recognized.

Any ideas what the problem might be?  I've reset CMOS multiple times, tried HDMI, different DisplayPort ports, different video cards.  No luck.  My video card is a 2070, but I also tried an older 980Ti card that I know works.  I keep thinking it might be the CPU, but it seems so unlikely that it would boot Windows and be defective.

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himerope Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 27 Aug 2021 Status: Offline Points: 20	Post Options Post Reply Quote himerope Report Post Thanks(0) Quote Reply Topic: Taichi x470 + 5800X - boots but no video Posted: 27 Aug 2021 at 6:47am
	Hi guys, I have a Taichi x470 motherboard, and I recently upgraded my CPU from a 2700X to a 5800X. I flashed the BIOS to 4.70 before I did it, and reset the CMOS. It boots no problem, and I can hear the Windows startup sounds and things, but there's no video signal, not even the BIOS boot screen. The monitor stays completely asleep. I tried downgrading to 4.60, and the same thing. I can swap in the 2700X and there's no problem, it boots perfectly with video. But if I put the 5800X in, while it will boot Windows, I can't get the video card to be recognized. Any ideas what the problem might be? I've reset CMOS multiple times, tried HDMI, different DisplayPort ports, different video cards. No luck. My video card is a 2070, but I also tried an older 980Ti card that I know works. I keep thinking it might be the CPU, but it seems so unlikely that it would boot Windows and be defective.

Khun_Doug Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 29 Mar 2020 Location: Poconos PA Status: Offline Points: 1025	Post Options Post Reply Quote Khun_Doug Report Post Thanks(0) Quote Reply Posted: 28 Aug 2021 at 2:59pm
	Hi Himerope, That reads to me as if the motherboard is not initializing the GPU. Probably some unexpected side effect of the CPU change. There are two things I would try. First, is it possible to temporarily move the GPU to the other PCI slot? That might be enough to get the motherboard to detect the GPU. That's clearly not a permanent fix, but it would give you more information. Second, using the CPU that works, I would go into BIOS and look for settings that can override the PCI slot settings. I had an EVGA motherboard that simply would not detect a PowerColor GPU about 20% of power-on. The system had no BIOS and no OS display. It would take a power-cycle to resolve the problem. I had to override the default in BIOS and force the slot to PCI3 to allow the GPU to be detected. I expect you might have something similar happening here.

Xaltar Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Joined: 16 May 2015 Location: Europe Status: Offline Points: 28053	Post Options Post Reply Quote Xaltar Report Post Thanks(0) Quote Reply Posted: 28 Aug 2021 at 3:48pm
	You can also try manually setting the PCIe gen to 3.0 for the slot you are using. Sometimes the "auto" setting can cause issues like this after a major hardware change. If it works you can try going back and setting it to auto again.