Both monitors stop working, but PC still running

[Ruslanets]

My both monitors start showing "no signal", but case/pump fans and RGB on them work well, as well as RGB on a graphics card.
I need to hold the Power button on the case to turn it off, only then I can turn the system back on again. Restart button does not work, for example.

It only happens when I play RDR2. Not sure about other titles, didn't play anything that demanding for a while.
It started happening about a week ago, although I played RDR2 for almost a month alreaady. I suppose it first happened when I set the settings to max possible, but it still happens with high-medium settings, so I'm not sure if that's the problem.
This does not happen when I'm working, browsing, or play something light like The Walking Dead.
My PSU is 750W, it must be more than enough for the hardware I have.
Afterburner logs do not show anything unusual at the time of the crash.

[emosun]

6 minutes ago, Ruslanets said:

My PSU is 750W, it must be more than enough for the hardware I have.

did you want to disclose what the hardware is 

[Ruslanets]

10 minutes ago, emosun said:

did you want to disclose what the hardware is or not

GPU: ASUS TUF GAMING Radeon RX 6800 XT
CPU: Ryzen 9 5900X
RAM: HyperX 2x16GB 3200
Mobo: MSI MAG b550m Mortar WiFi
PSU: Cooler Master MWE Gold 750 Full Modular
Drives: 2 SSD, 1 HDD

[Robertshipley]

Check all your power connections to motherboard and GPU

[Ruslanets]

11 minutes ago, Robertshipley said:

Check all your power connections to motherboard and GPU

I replugged all the PSU cables, didn't help

[Ruslanets]

Still having the same issue.
More info:
Wireless peripherals show a loss of connection, and Discord calls drop, so PC is probably not working at all, IDK why the RGB works.
It only happens when I play demanding titles (RDR2, Marvel's GOTG, It Takes Two, and Forza Horizon 5). This does not happen when I'm working, browsing, or playing something light like The Walking Dead or New Vegas.

Afterburner logs at the time of the crash show somewhat unusual behavior in the last 8 seconds (not sure if it's prior to shutting off the monitors, or after) - there's a sudden dip in GPU power consumption and rapid temp increase on the CPU (+7C in 8 seconds).

Any help will be much appreciated

[Ruslanets]

So, here's the list of things that hasn't helped me so far:

• Updating bios.
• Updating GPU drivers, AMD software, and mobo drivers.
• Connecting the GPU to the PSU with two separate 8-pin cables instead of piggytailing.
• Disconecting one of my two monitors from the GPU and playing with one only (kinda helped - didn't have such issues in RDR2, It takes two and GOTG, but Forza Horizon 5 still can't run for longer than 30 minutes).
• Removing a decorative rubber duck from the case.
• Changing an outlet and extension cord.
• Moving RAM from 2&4 to 1&3 slot.
• Disconnecting my hard drive and booting with SSDs only (idk what it was for, but some commenters online suggested it helped in their case).
• Unplugging the GPU from the PCIe slot and plugging it back (sadly, there's no way to fit it in the second slot, as there are USB and Audio connectors right below it, so the card doesn't fit).

Surprisingly, I ran Furmark on 100% load for both GPU and CPU for almost an hour (it is way longer than any game allows me to play) and there were no issues so far. I can't even think of a good reason for this issue to happen during gaming.