My PC was working normally earlier today. After shutting it down and turning it back on later, the fans spin but the monitor stays blank, and the mouse and keyboard do not light up. The case or motherboard indicator remains solid orange instead of blinking normally, so it seems the system is failing before or during POST. I've already cleared the CMOS, reseated all four RAM modules, reseated the CPU, and disconnected and reconnected the major components. Is there anything else I should test before taking it to a repair shop or replacing parts?
The system has an Intel i3 4th-generation CPU, an ASRock B85M Pro4 motherboard, 12GB of RAM made up of two 2GB and two 4GB modules, a 450W PSU, and no dedicated graphics card. It's old, but it was working fine until this happened.
3 Answers
Disconnect all storage drives as another diagnostic step. A failing or shorted drive can sometimes prevent the system from reaching POST or displaying BIOS. If the BIOS screen appears with the drives removed, reconnect them one at a time to identify the problem. If there is still no display with only the minimum hardware connected, the issue is more likely the PSU or motherboard than Windows or the storage.
Try a bare-minimum boot: motherboard, CPU and cooler, one RAM stick, PSU, and monitor only. Disconnect every storage drive, USB device, and other expansion hardware. If it still does not reach BIOS, test each RAM module individually and try a known-good power supply. Booting with no RAM can also be useful because a working board should normally report a memory error through beeps or diagnostic indicators. If none of those tests changes anything, the motherboard, CPU, or PSU may have failed, and replacing parts on this older platform may not be worthwhile.
Start with one RAM stick at a time. Try each module by itself in the slot recommended by the motherboard manual, then repeat with the other slots if necessary. The orange indicator may point to a memory problem, although the exact meaning depends on the board. Also reseat both the 24-pin motherboard connector and the CPU power connector.
The motherboard is an ASRock B85M Pro4. I’ll check the recommended single-stick slot and test each module separately.