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Question My custom built PC is no longer detecting anything plugged into the motherboard

May 15, 2020

My custom-built desktop from around 2011 no longer seems to be recognizing anything plugged into the motherboard (display included).

This all started happening today after I noticed a strange revving noise coming from it this morning. My initial thought was that one of my hard drives was dying, so I unpowered/unplugged the computer (as well as the culprit HDD) and then subsequently turned everything back on again to see if this truly was the case. I noticed that it was still making this noise, so my next thought was to remove the front panel and see if it was one of the fans. Luckily, I was able to figure out that the bearings on one of my fans was failing (it was having a lot of trouble spinning), so I put everything back together and went on my way to start looking up replacement fans I could purchase. No big deal...

However, the next time I turned my computer on, I noticed that something was wrong. While it was able to turn on and all the fans were spinning, I noticed that my monitor (ASUS VE247), keyboard (Corsair Vengeance K70 RGB) and mouse (Razer Deathadder) did not come on at all like they usually would. I looked at the back of my computer and saw that the ethernet port light was still lit up, so I wasn't thinking that I fried my motherboard (Gigabyte Z77X-UD5H) or anything. I tried to turn off my computer after this, but the button on the front wouldn't do anything at all when I held it down, even though it was lit up. I ended up having to turn it off using the power switch on the PSU, unplugged everything, and had a look inside the case to see if maybe one of the cables came loose. Everything was fine as far as I could tell, and I didn't notice anything burnt on the board.

So I tried powering it back on again but...this time, my computer would turn on for a second, off for a few, on again for a second, etc. Looked online and saw some people talking about how clearing the CMOS can sometimes fix this boot loop issue. So I unplugged everything once again, pressed the CMOS_SW button on the motherboard, waited 30 seconds, and then tried firing it back up again. This time, it didn't loop and I hoped that I would maybe be in the clear. However, when I tried plugging my peripherals back in, I ended up with both similar and new issues. My monitor and keyboard still could not be detected, yet my keyboard seemed to be getting some kind of power because the default LED color scheme loaded into its BIOS was lit up. Also, the ethernet port wasn't lighting up anymore like it used to.

I tried getting my monitor to work by connecting it via HDMI, DVI, and VGA to both my graphics card as well as the integrated graphics slots on my motherboard and changing the input source on my monitor to match. Wasn't able to get anything to display at all. I also tried plugging my mouse into my laptop, and it was able to detect it just fine. So I'm thinking all of my peripherals are okay, there's just something wonky going on with the motherboard.

This is basically where I'm at now. Sometimes when I leave the computer on for a few minutes, it restarts on its own, while other times it just stays on. Completely random.

I'm hoping this issue can be fixed without having to buy a new motherboard, as all the fans (including on the GPU and CPU) seem to be getting power.

Here are my specs:
Motherboard: Gigabyte Z77X-UD5H
OS: Windows 10
RAM: Corsair Vengeance DDR3 1600 (PC3 12800) 16GB (4x4GB)
CPU: Intel i7-3770k 3.5-3.9GHz
GPU: EVGA NVidia GeForce GTX770
PSU: Corsair HX750
Keyboard: Corsair Vengeance K70 RGB)
Mouse: Razer Deathadder
Display: Asus VE247