I just finished assembling my first PC, but it powers on without displaying anything or reaching the BIOS. The keyboard, mouse, power supply, and monitor are connected, and all the fans—including the CPU, GPU, case, and PSU fans—are spinning. Nothing seems to be overheating, and the system stays quiet and steady. The case power light slowly flashes on and off.
I'm using a 650W power supply, upgraded from a 500W unit, and everything was connected by following build guides and the manuals. I eventually noticed that my RTX 3060 requires both an 8-pin and a 6-pin PCIe power connection, while I initially thought the power supply only had one suitable connector. Could that be the reason it wasn't booting?
2 Answers
Check the PCIe cables that came with the power supply. Many GPU connectors are 6+2-pin cables, meaning the extra two pins can separate from the main six. Your RTX 3060 needs both its 8-pin and 6-pin sockets powered. If the cable supports it, the same PCIe cable can usually provide both connections, including through its daisy-chain connector. Make sure you’re using PCIe/GPU cables rather than CPU power cables, and don’t mix modular cables from another power supply.
If the GPU power connections aren’t the issue, try the basic troubleshooting steps: check whether Caps Lock responds, look for motherboard diagnostic LEDs, and—if the processor has integrated graphics—temporarily remove the graphics card and test whether the system reaches BIOS. Also confirm that the monitor cable is connected to the graphics card when the card is installed.
I didn’t realize the same PCIe cable could connect to both sockets. I plugged in the 8-pin and 6-pin ends, and the PC is working now!