My monitor is not starting (no power)

“I bought an ASRock H610M-HVS motherboard to upgrade my RAM and processor. The system turns on, but initially, the keyboard, mouse, and monitor didn’t light up. After trying with only one RAM stick, the mouse and keyboard work, but the monitor remains unresponsive. I have two RAM slots, and if I use the upper slot, neither the mouse nor the keyboard function, as if the motherboard is faulty. I’ve ruled out issues with the monitor, cables, or graphics card by testing them on my old PC, where they work fine. I also attempted connecting the monitor to the integrated graphics, but it still doesn’t work.”