I upgraded my CPU and installed a large Noctua air cooler. I had to remove and reconnect the graphics card during the installation. Now the system powers on, the fans spin, and the lights come on, but the monitor says there is no signal. The case power button also does not shut the computer down, even when I hold it for more than 30 seconds, so I have been using the power strip to turn it off. I have already reseated the RAM and tried resetting the CMOS with a screwdriver, but neither helped. What should I check next?
2 Answers
Start by checking the graphics card carefully. Make sure it is fully seated in the PCIe slot and that every required 6-pin or 8-pin power connector is plugged in. Also verify that the monitor cable is connected to the graphics card rather than the motherboard, unless the new CPU has integrated graphics. While you are checking, reseat the motherboard’s main ATX power cable and the CPU power cable near the top of the board.
Because the CPU was replaced, focus on the CPU installation and compatibility. Confirm that the processor is oriented correctly, the socket has no bent pins or damaged contacts, and the cooler is not mounted so tightly that it is putting unusual pressure on the board. Check that the motherboard BIOS supports the new CPU, especially if it is an older board. A CPU or RAM failure can prevent the system from reaching the stage where it outputs video, even if the GPU is working.
I tried holding the power button for more than 30 seconds, but the system still stayed on, which is why I ended up switching off the power strip.