Start from scratch. Make sure you installed the processor and graphics card correctly. Attach the graphics card into slot PCIEX16(G5). For testing purposes, mount one RAM module into slot A_2. Install one NVME SSD into slot M2_2 or conventional SSD using an SATA cable. Plug in all power connectors on the motherboard [ATX_POWER, ATX_12V_1, ATX_12V_2]. Insert an HDMI cable into the back port of the motherboard and one for the graphics card. Fire up the computer. Let us know what's happening.