Good day. purchased Gigabyte B550 Aorus Elite V2 and R7 5800x processor. Before that, there was R7 2700 and B450 with which the 6700XT video card worked. I changed the processor with the motherboard, installed a video card. PC starts, 1 long - 2 short, no image. I put an old NVidia 7600gs video card in the second slot, it started up. I went into the bios, everything is fine. I put 7600 in the PCI Ex x16 slot, the same error on the video card. Put 7600 in the second slot and in the first 6700ХТ. It loads, enters the BIOS, does not see the video card in the first slot in the info system. BIOS version F14. Updated BIOS to the latest version, did not help. I updated the BIOS in the MB B450, put the 5800X processor there, the situation repeats itself as on the new MB. I inserted the 5800X processor back into the new MB, in the BIOS settings I chose pci e x16 bifurcation from auto to pci1 x8 / pci 2 x4. After that, the 6700XT card started up and works. The PC is booting up. All cards that were used during the check are in good condition and tested on another PC. The problem was with the processor. It does not work on the PCIex x16 bus, only in x8 mode.