When I press the power button, the desktop starts up, the fans immediately ramp to full speed, and all the case LEDs turn on. However, it never reaches the BIOS or displays anything, and neither the keyboard nor mouse receives power when connected to the front or rear USB ports. I'm not seeing any motherboard error lights or codes. What should I check to figure out whether the problem is the RAM, CPU, graphics card, motherboard, or something else?
3 Answers
That sounds like the system is failing its initial POST check. If your motherboard has diagnostic LEDs or a small display, check whether one stays lit or shows an error code. Since you don’t see any, try testing with only the CPU, one stick of RAM, and the graphics card connected. Disconnect drives, USB devices, and other expansion cards, then see whether it can reach the BIOS.
A useful next step is clearing the CMOS and reseating the RAM, graphics card, and power connectors. Test each memory stick individually and try different RAM slots. If the computer still gives no display or USB power, connecting a small motherboard speaker may provide beep codes that help identify the failed component.
It’s too early to conclude that the whole PC is dead. A loose power connector, bad RAM, failed power supply, motherboard problem, or CPU issue can all cause fans and LEDs to run without completing POST. Start with a minimal hardware test and verify that the CPU power cable and motherboard power cable are firmly connected.
I checked the board and couldn’t find any diagnostic lights or a code display, so I’ll try starting it with only the essential components connected.