This is my first post so bear with me, but I hope to help someone else avoid the same headache.
I have looked EVERYWHERE to resolve my issues and eventually stumbled upon the solutions through trial and error. (ASUS support was WOEFULLY inadequate)
The Build:
- 1 x ASUS ROG Crosshair VII Hero (Wi-Fi) AM4 AMD X470 SATA 6Gb/s USB 3.1 ATX AMD Motherboard
- 1 x Cooler Master MasterLiquid ML240R Addressable RGB AIO CPU Liquid Cooler
- 1 x G.SKILL TridentZ RGB Series 16GB (2 x 8GB) 288-Pin DDR4 SDRAM DDR4 2933 (PC4 23400)
- 1 x AMD RYZEN 7 2700X 8-Core 3.7 GHz (4.3 GHz Max Boost) Socket AM4 105W YD270XBGAFBOX
- 1 x Cooler Master V1200 - Fully Modular 1200W 80 PLUS Platinum PSU
- 2 x MSI Radeon R9 390X DirectX 12 R9 390X GAMING 8G 8GB 512-Bit
- 1 x Logitech G910 Orion Spark RGB Mechanical Gaming Keyboard
- 2 x WD Black 3TB Hard Disk Drive - 7200 RPM SATA 6Gb/s 64MB Cache 3.5 Inch - WD3003FZEX
- 2 x Crucial BX100 500GB SATA 2.5 inch Internal Solid State Drive (SSD) CT500BX100SSD1
- 1 x Cooler Master Cosmos II - Ultra Tower Computer Case with Metal Body and Hinged Side Panels
- 1 x M.M.O. 7 Adjustable Gaming Mouse
The Issues:Prior to BIOS v. 0601:
- Long delays in explorer activities (creating folders, files, enumerating favorites)
- Periodic hangs when playing or browsing
- Screen periodically goes black for ~30 seconds and then recovers
- BSOD
- Memory won't run at XMP speeds
- Occasionally hard hangs requiring a forced reboot
Post BIOS v. 0601:
- Occasional long delays in explorer activities (creating folders, files, enumerating favorites; less predictable, but still present)
- Periodic hangs when browsing (I suspect it has to do with the explorer issue)
- Screen periodically goes black for ~30 seconds and then recovers several times (usually after a cold boot)
- PCI enumeration stuck at 8x,1x (Crossfire no longer functions)
The Fix:
- Manually tune the memory - the XMP settings were not applying correctly for me
- Disable Gear Down Mode and Bank Group Swap (these were causing BAD cache misses and buffer flushes in volatile apps like Chrome and Edge)
- In the Extreme Tweaker -> PCIE config, there are 3 tests, 2 of them are disabled by default but BIOS 0601 sets them to Auto. Disable tests 1 and 2. PCI config will immediately correct to 8x, 8x and Crossfire will work again.
I hope this saves someone else from an unnecessary RMA and allows them to enjoy the glory of their build.