According to your DXDiag.exe you have three files that are having problems:
1) mDNSRESPONDER.exe - This a part of Bonjour Service (APPLE program) - What Is mDNSResponder.exe / Bonjour and How Can I Uninstall or Remove It?
2) CORSAIR SERVICE.exe - Not sure what Corsair Hardware is used by this Corsair Service but here is one problem from Corsair Forum: CUE and Corsair.Service using a lot of CPU and RAM - The Corsair User Forums
3) FALLOUTNV.exe - This concerns the game FALLOUT/NEW VEGAS - This is one problem with that game at Steam Forum: "Couldn't Find FalloutNV.exe" :: Fallout: New Vegas General Discussions
I would download ASRock AMD Graphic Driver and see if it installs from here: ASRock > B450M-HDV
| Description | THE | Size | Date | Download | |
|---|---|---|---|---|---|
| AMD all in 1 with VGA driver ver:18.10.20_NHDA | Windows® 10 64bit | 719.60MB | 2018/10/16 |  Global | China |
Also I would update the motherboard's BIOS to the latest from here: ASRock > B450M-HDV
BIOS
Please read the information below before downloading or updating your BIOSWe don't recommend users to update the BIOS if their system is already running normally. ASRock assumes no responsibility for any damages caused by improper operations of downloading or updating the BIOS. Before you download or update the BIOS, please read " 
(How to Update)" below carefully. After updating BIOS, all the settings will be reset to the default.
(How to Update)" below carefully. After updating BIOS, all the settings will be reset to the default.| Version | Date | Size | Update BIOS Under / How to Update | Description | Download | |
|---|---|---|---|---|---|---|
| 1.20 | 2018/10/12 | 7.82MB | Instant Flash | 1.Support multi-language for DRAM information. 2.Update Raven VBIOS and GOP 3.Keep XMP setting after system resuming from G3 state. 4.Change onboard display rule for Raven CPU. 5.Correct Boot Menu[F11] display. |  Global | China |
I would also run in a elevated COMMAND PROMPT - SFC /scannow - to be sure your Windows installation is not corrupted or missing vital files.
Here is the latest RX 580 Driver from AMD Download page: Radeon™ RX 580 Drivers & Support | AMD
Then I would use this basic method of install and removing AMD Drivers to prevent conflicts with existing drivers:
install AMD driver:
1) Download the correct AMD Full Set of drivers from AMD Support. Make sure your Windows is fully updated via Windows Update. Windows Must be fully updated because the latest AMD Drivers requires all the latest "Optional" and "Recommended" updates to be installed.
2) Use Windows Uninstall to uninstall current AMD driver and software and disconnect the internet from your computer. Then use DDU (Display Driver Uninstaller) Display Driver Uninstaller (DDU) from Wagnardsoft Forum in Safe Mode. This will eliminate all traces of the AMD driver and software from your computer.
Delete C: \ AMD folder from the Root Directory. Reboot
3) Go to Device Manager and click "Display Adapter" and make sure you are on the MS Basic Display Adapter. If not, uninstall the AMD driver using Properties.
4) Try reinstalling the AMD FULL SET OF DRIVERS that you have downloaded manually. Make sure you disable the Internet to prevent Windows from installing a newer version. So configure windows to prevent it from updating drivers via windows update. So it has been mentioned to disable any anti-virus programs before installing AMD Drivers.
5) If the new AMD drivers installs and works correctly, delete again the C: \ AMD folder from the root directory. To save space on the HDD.
6) Enable both the Internet and Anti-Virus program (if applicable).
7) Go back to Device Manager and check your GPU card driver is working and identified correctly.
