I've built a new rig on Asus TUF x570 Gaming Plus motherboardwith latest 1404 bios (later replaced with Gigabyte Aorus Elite x570), 32GB of G.Skill 3200MHZ RAM, MSI RTX 2600 Ventus (later replaced with another of the same model and finally with a Gigabyte RTX 2070 Super 3X OC 8GB), 650W PSU (later replaced with a 1000W PSU). Dual OS - Windows 10 1903 and Ubuntu 19.10. Nvidia driver on Windows 441.12, On Linux 435. Same behaviour using all components and OSes. The only common items that I only have one of is the CPU so it has to be the item that is causing the problem.
It seems no GPU using PCIe 3 can work in the 16x slot. If I set the PCIe to version 2 GPU works fine in the first slot. If I set it to 3.0 or auto the PC locks up immediately on black screen when NVidia driver is installed if the GPU is in the first slot where it attempts to use 16 lanes of PCIe 3.0. If I place the GPU in the second PCIe slot that has only 4 lanes it works fine.
I tried various things from replacing all the parts other than the CPU, resetting bios settings to using different settings. Nothing helps. The moment a card installed in a PCIe 16x slot tries to use PCIe version 3.0 system locks up. There is no crash dump file.
I've found a similar story online where PC was crashing if gpu was placed in the first PCIe slot. That person said their CPU had a bent pin. I looked at my CPU under a microscope very carefully and there are no bent pins, no missing pins.
I find it very difficult to believe a faulty CPU could work perfectly fine using all 16 lanes for PCIe version 2 and crash the moment version 3 is enabled, but at the same time people online are using 16 lane PCIe 3.0 GPUs in motherboards with x570 chipset and Ryzen CPUs so perhaps I do have a faulty one. Please let me know what do you think. Although it is easy for me to exchange most of PC components in the store I buy them from they are reluctant to exchange CPUs that have been used. I would rather know for sure this is a CPU issue and not some BIOS incompatibility everyone is experiencing, but only I mentioned.