I recently performed some routine maintenance on my computer, which includes specs like an Aorus B450 Pro Wifi motherboard, Ryzen 3600 XT CPU, Corsair Vengeance DDR4 3200MHz RAM, and an RX 7600 GPU. After cleaning out all the dust and reassembling everything, I realized I forgot to connect the monitor cable. Once I connected it, I saw no video output, and my keyboard and mouse weren't turning on either. The DRAM LED was blinking, while the CPU LED stayed lit. I tried removing the CMOS battery, resetting the BIOS, and changing the RAM slots, but nothing worked. When I hit the power button, the motherboard's RGB lights and fans spun up, but it didn't boot. I'm really worried about this since I rely on my PC for work. Any ideas on what might be wrong?
3 Answers
Have you tried using the onboard video port from the motherboard instead of your GPU? It’s possible that a CMOS reset could’ve changed your display settings in the BIOS.
Does your system make any beep sounds when you boot it up? That could be a way to diagnose what's going wrong. You might need to connect a speaker to the motherboard to hear any beep codes being issued, which tell you what the issue is.
First off, you might want to double-check all your power cable connections; sometimes, things can get loose during reassembly. If that doesn't work, there's a chance something might've gotten damaged, either to the CPU or the motherboard. It’s worth taking a close look.
I hear you! But make sure to eat something first before diving back in. You don’t want to be troubleshooting on an empty stomach!
That was actually the fix for me! I spent all day on mine, and it turned on again after just reassembling everything properly.

I don’t have a speaker connected either, but from my manual, it says there should be a single short beep if everything’s fine. So far, I've heard nothing, which seems a bit worrying.