I returned home after being abroad for a year and tried to use my desktop PC, but the monitor remains completely black and reports "No connection detected." The computer appears to power on, and the keyboard lights up, but the mouse and USB sound card do not initialize as they normally do when Windows starts. The monitor works normally when connected to my laptop through DVI, and I have already tried different video ports and cables on the desktop.
I have reseated the GTX 1060, tested the RAM sticks individually in different slots, tried another power supply, and removed the CMOS battery for about ten minutes. The system uses an ASUS H110M-PLUS motherboard, an Intel i7-6700 processor, a GTX 1060, and 16 GB of RAM. The motherboard has no diagnostic LEDs, only a speaker, but it produces no beep codes either.
Could this be a failed POST, RAM or GPU problem, or possibly a motherboard or CPU fault? What would be the best way to narrow it down?
3 Answers
USB lights only show that the board is supplying power; they do not prove the computer passed POST. Start with a true minimal-POST setup: disconnect all drives and USB devices, leave one RAM stick installed, and reseat the 24-pin motherboard connector, the CPU power connector, and the GPU power cable. Clear CMOS with the power supply switched off and unplugged, following the board manual.
The i7-6700 has integrated graphics, so you can also remove the GTX 1060 completely and connect the monitor to the motherboard’s video output. If that produces an image, the issue is likely related to the graphics card, its power connection, or the PCIe slot. If there is still no display, the lack of beep codes may point to a board, speaker, CPU, or power-delivery problem.
Since the monitor works with the laptop, the display itself is probably fine. Try both graphics paths: first test the GTX 1060 with its power connector firmly seated, then remove it and use the i7-6700’s integrated graphics through the motherboard output. A successful picture from only one path would identify the likely culprit.
If neither configuration shows anything after a proper CMOS reset and minimal setup, the next useful test is another known-good compatible RAM kit or a bench test outside the case. At that point, the motherboard becomes more suspicious than the monitor.
In some systems, repeatedly clearing CMOS and allowing the board to retrain the memory can help after a long period without use, but it is not a substitute for checking the power connectors and testing one component at a time.
Before assuming the CPU or motherboard is dead, test the system with only the motherboard, CPU and cooler, one RAM stick, power supply, and display connected. Make sure the RAM is in the slot recommended by the manual and clean out dust before reseating it. Disconnect storage drives and all unnecessary peripherals so a faulty device cannot interfere with POST.
Also check the power-supply swap carefully: if either supply is modular, use only the cables that came with that specific PSU. Modular cables can have different pinouts even when the plugs fit, and mixing them can damage components.
The motherboard is an ASUS H110M-PLUS, and it has no diagnostic LEDs. I tried the built-in speaker, but it never produces any sound during startup, even after clearing the CMOS.