Question [Boot] PC won't boot or post with wrong or both display connected

[Peott]

I have built several computers in the past and this build is the first to have ever given me any kind of grief... https://pcpartpicker.com/list/dPvW9G

Symptoms:

• When booting with both my monitors, PC starts, fans run, power LED is on, but no graphics are sent. I don't think it even goes post-Post, since pressing the power button to restart does nothing. The only way I can get out of this situation is to switch the power supply off
• When booting with my main monitor (32" Samsung S32D850 at 1440), same exact situation
• When booting with my secondary monitor (24" LG 24GM77 at 1080), the PC boots fine

I've tried pretty much everything, and this is the only situation I can get it to boot: with my secondary, vertical monitor. I then plug my main monitor after I hit the Bios screen and it's fine from there. I tried both monitors through any combinations of the three DP ports I have available on the GPU. I also tried to tweak the GPU setups, to no avail. I do not have HDMI cables to try it out with, but I typically use DP.

All drivers are up to date; Windows update, BIOS, graphics. The Device Manager doesn't show any unknown devices. The PC runs fine when it does run, so I am not seeing any other issues but for my inability to play one of the only two games I run, Battlefield V (View: https://www.reddit.com/r/BattlefieldV/comments/em3ezc/freeze_bf5_graphics_freeze_on_brand_new_system_it/)

Thanks for any tips on how to fix this! This is my first AMD build and it's had nothing but trouble getting started, so I'd love to get it running and for it to maybe change my mind.

EDIT: I have a Corsair AX850W PSU, and I have absolutely no issue when using my GTX970 instead of the 5700.

 

[dotas1]

I have absolutely no issue when using my GTX970 instead of the 5700.

This should have been your biggest indication. Try the GPU in another system to verify its the problem and if it is, rma it.

 

[Peott]

This should have been your biggest indication. Try the GPU in another system to verify its the problem and if it is, rma it.

This current GPU is actually already a replacement for an RMA When I got the original one i ran into the same issue; I hadn't tried it with only one display.

When I got the replacement, I did some more troubleshooting and tried it with just one display, which is how I got it to work under that one condition.

Here's what else I tried:

• Updated GPU driver to latest release (20.1.1)
• Updated motherboard chipset driver
• Ensured all display drivers are fully up to date
• Tried setting bios PCIe setting to Gen3
• Tried different cables/combinations of cables/monitors

But still nothing for now...

I did keep my old motherboard/CPU/cooler/GPU assembly, so I will try that next

 

[dotas1]

So you did try with HDMI as well?
Can you try the card in another system?

 

[Peott]

Well, I AM stupid.

It was the cable.

I HAD tried the following: monitor that didn't work, with the cable of the monitor that worked, to the GPU output that worked. That hadn't fixed anything.

Today I tried booting the previous setup with the second monitor turned-off, rather than unplugged. That didn't do anything either.

Hence, prior to re-building my prior system with my current PSU and GPU to test which would have been a wee hassle, I found myself a completely different DP cable, and tried booting with both monitors: the one that always worked kept its cable, the one that didn't with the new cable.

And lo: it booted just fine.

This is doubly-weird as both cables I used before were the same (Amazon basics Display Port)! Not to mention, they both DID work, since once booted, I could add the other screen. Finally, in my previous system, both cables worked fine.

So I have no idea why this setup gave me that much grief. But I have a working system now with dual monitors, kept my DP setup, and above all, I was finally able to do my cable management and close the damn box.

Thanks all for reminding me to NOT take anything for granted and test everything I am able to test, no matter my own preconceptions and assumptions!