Question No response/signal on cold/first boot ?

Nov 29, 2020
I build a PC last summer, and started having the following problem about 1 or 2 months after: When booting my PC for the first time in about a few hours, the monitor shows the windows login screen, but when pressing keys there's no response and after 5-10 sec the monitor goes to "no signal". The computer is still turned on with fans spinning and light in keyboard and motherboard. I've tried a lot of things to fix it:
  1. Unplug and replug everything: cables. monitors etc.
  2. Exhange DP cable and monitor with a new one
  3. Re-assemble motherboard, RAM, GPU and check connectors
  4. Using HDMI cable
  5. Rechecked all components compatibility
  1. Settings in BIOS: Fast boot disabled/enabled, XMP enabled, external graphics card selected and booting order correct. Also correct voltage on RAM and drive
  2. Update BIOS
  3. Update GPU drivers, chipset drivers, check if monitor driver is needed
  4. Controlpanel -> Hardware & sound -> power -> "Change what the power bottom does" -> Disable "Aktivate fast boot"
  5. Freesync compatible and enabled
  6. Windows 10 update
  7. Windows 10 reinstalled
The only thing that seems to work is turning off the PC, holding in the power bottom for 30 sec to empty for power. This makes the PC boot up fine the next time, but after first boot it's bck to normal.

My system is:
  • CPU: AMD Ryzen 5 3600
  • GPU: GIGABYTE Radeon RX 5600 XT Gaming OC
  • PSU: GIGABYTE G750H 750 W
  • Motherboard: GIGABYTE B550 Aorus Elite
  • RAM: G.skill RipjawsV DDR4-3600 C16 DC 16 GB CL16-16-16-36
  • Harddrive: Kingston A2000 M.2 NVMe SSD 500 GB
  • Monitor: AOC Gaming C24G1 - WLED 24" AMD FreeSync VA 1ms
Due to the system responding to the power drain i'm thinking it's a PSU problem but im not confident enough to do a warrenty claim.