I recently returned home after being abroad for a year and tried to start my desktop PC, but the monitor remains black and reports "No connection detected." The monitor works normally when connected to my laptop over DVI, so the display itself seems fine.
The computer powers on and the keyboard lights up, but the mouse and USB sound card do not. Those devices normally light up when Windows reaches the login screen, so I'm concerned the system may not be completing POST. I've tried every video output I could find, tested the RAM sticks individually in different slots, reseated the graphics card, tried another power supply, and removed the CMOS battery for about ten minutes.
The system uses an ASUS H110M-PLUS motherboard, GTX 1060 graphics card, i7-6700 processor, and 16 GB of RAM. The motherboard has no diagnostic LEDs, only a speaker, but it produces no beep codes either. What else should I check before assuming the motherboard or CPU has failed?
4 Answers
Be especially careful if the replacement power supply is modular. The detachable cables are not universally wired, so cables from one PSU must not be reused with another even if the plugs fit. Using mismatched cables can damage the motherboard, drives, or graphics card. Also confirm that the monitor cable is connected to the GTX 1060 when the card is installed, rather than the motherboard’s video ports.
Memory training can sometimes cause a blank screen for a while, particularly after changing RAM or clearing CMOS. If you can eventually reach the firmware settings, disable any memory fast-boot option so the board checks and trains the memory on every startup. If there is still no display in a minimal configuration with the GTX 1060 removed, the remaining likely causes are the RAM, motherboard, CPU, or a power connection rather than the monitor.
Before replacing expensive parts, double-check the RAM slot recommended by the motherboard manual and cleanly reseat the memory. With the PSU unplugged, hold the case power button for 15–30 seconds to discharge it, then reconnect everything and try again. Dust or a slightly poor connection can prevent POST, so cleaning the slots and contacts carefully may help.
USB lights only show that the board is supplying power; they don’t prove that the computer passed its power-on self-test. Try a true minimal-POST setup: disconnect all drives and USB devices, leave one RAM stick installed, reseat the 24-pin motherboard connector, the CPU power connector, and the GPU power cable, then clear CMOS with the power supply switched off and unplugged. Since the i7-6700 has integrated graphics, you can also remove the GTX 1060 and test the motherboard’s video output. If that works, the graphics card or its power connection becomes the main suspect.
The H110M-PLUS doesn’t have diagnostic LEDs, only a speaker, and it doesn’t produce any sound during startup. I’ll try the minimal setup and integrated graphics test.
I tried the discharge procedure, reseated the RAM, and cleared CMOS, but unfortunately the behavior didn’t change.