I've been encountering strange behavior since I built my computer and after trying to single out the problem I'm suspecting that my motherboard is the issue. My mobo is the Gigabyte x470 Aorus Ultra Gaming and initially when I first booted up the computer, there was no display and at the time I had the RX 580 graphics card to which I was able to resolve it by plugging in individual pcie power cables (2) to the graphics card and was able to post afterwards. But, an issue I noticed while in windows is that bringing the volume control, the screen would go black for an instant and then resume. I was able to fix that by changing to another display, which was another hdtv at the time. Things were fine until Windows May update came along, 1903 and my system started showing other odd behaviors.
I am only able to post now only on a cold boot and if I try to restart my system I noticed that the led on my motherboard doesn't cycle through (cpu, cpu 1, gpu, boot) and I get a no display. I had attempted to isolate the issue and was able to replicate this after installing my graphics card driver, but afterwards once I finish installing all of my drivers the problem goes away temporarily. Once I begin installing other applications, such as GNS3 the no display behavior comes back and it occurs when I am maximizing videos and switching tabs in a particular pattern. I ended up cleaning out my computer (I do it once every two weeks) and I have rebuilt my computer several times trying to see if there was a seating issue, loose cables, or any obvious clues leading to the issue. The parts from my first build was carried over to my current computer namely, the RM850X, WD Blue 1TB, WD DVD-RW drive, and USB 2.0 internal card reader.
I upgraded my graphics card recently to a GTX 1080 ti, it was used and had oil residue from the thermal pads which prompted me to clean the card and reapply thermal paste before installing the card. I noticed that one of the components on the pcb was loose, I nudged it in place and reassembled the card. The new card posted, and worked fine and ran a stress test for several hours and it passed it. I also overclocked the card to see if there are any stability issues and managed a 150mhz overclock on the core and 100 mhz on the ram stable. After restarting several times however the same issue would appear again with no display and my computer will only post once I shut it down completely and restarted it. I have tried resetting the cmos several times with all of my hardware installed and with one stick of ram, no gpu or drives installed. I noticed when I reset the bios that way my mobo worked for a time without issue but then after awhile I'll experience those symptoms again. My RX 580 was another thing that was carried over to this build and didn't experience that issue.
Summary of the steps I took
Update the bios, rebuilding computer, isolating each hardware component, reseating graphics card in other pcie slots, testing graphics card in another computer, reapplying thermal paste, trying 2 individual pcie power connects, trying single pcie power connectors, booting without any hard disks, booting without the internal usb 2.0 header populated, changing graphics card (gtx 750 with micro hdmi and vga, rx 580 with hdmi, gtx 1080 ti with hdmi) trying older drivers, downgrading bios version, resetting bios via jumper, resetting bios by loading optimal defaults, turning off amd-v and iommu, and changing boot order.
Ryzen 5 2600x (stock)
Gigabyte X470 Aorus Ultra Gaming
G.Skill Ripjaws V 2x8GB 3200mhz cl16
Samsung NVME 970 evo 500GB
WD Blue 1TB
MSI Gaming X GTX 1080 ti (Current Card, stock settings)
RX 580 Red Devil (Old Card, not in use)
PNY GTX 750 2GB (Old Card, not in use)
Windows 10 x64 Pro version 1903
Nvidia Driver 436.30
Display is a roku tv
No display after restarting upon installing Graphics Driver and GNS3
No display when maximizing videos and switching tabs within the browser in a specific pattern