So here's a weird problem that appeared last week. I will explain it in the best detail possible.
Recently, I've been experiencing an issue when waking up the computer from sleep or hibernation. The system resumes correctly, except the video output - the Windows desktop flashes for a split second, and then the screen immediately turns black. Not black as in "black colored background", but completely black - even the monitor backlight turns off.
Funny enough, the monitor LED indicator doesn't blink (as it does in sleep mode), but glows continuously. I believe the graphics card is stuck in some sort of "resolution switching" loop. I know for sure I haven't touched any critical settings or drivers - the problem appeared completely on its own. The monitor appears to be in the working state, as there's no "No Signal" message displayed.
I've tried everything - clean installing the latest drivers, alternating from Windows 7 to Windows 10, switching from DVI to HDMI connection, updating the system BIOS, turning off HPET and ErP in BIOS, disabling PCI Express Link State Power Management - literally nothing worked. To temporarily solve the problem, I have to either power-cycle the monitor 5-6 times, disconnect and reconnect the HDMI cable the same number of times, or simply hit the reset button on my computer.
However, I've noticed a pattern - the problem appears only if I leave the system in sleep mode for an hour or so. If I put it to sleep and wake it up shortly after (2-3 minutes), everything works fine. Also, note that the problem appears only when sleeping and hibernating - cold boot and restart works totally fine. The system isn't frozen by any means, everything works fine except there's no image displayed on the monitor. One more thing - on a rare occasion, the Radeon Software might crash when this problem occurs.
I suspect the issue is either with the graphics card itself, the power supply, or the motherboard. I don't believe the monitor is the problem, since it works fine with my laptop over HDMI. If I get my hands on a spare graphics card, I will test it to see where the problem lies.
CPU: AMD FX-4130
RAM: 8GB DDR3 (2x 4GB 1333 MHz)
GPU: Sapphire Radeon HD7750 1GB DDR5
Drivers: tested with both 19.9.2 and 20.4.2
Disks: Kingston A400 240GB SSD and WD Blue 1TB HDD
MB: Gigabyte GA-970A-DS3P (rev. 1.0, BIOS F2j)
Monitor: LG 22EA53 (22" Full HD IPS, HDMI)
PSU: Enermax NAXN Basic 500W
OS: tested on both Windows 7 64-bit and Windows 10 64-bit