Phantom Gaming B850I Lightning Dual GPU
Printed From: ASRock.com
Category: Technical Support
Forum Name: AMD Motherboards
Forum Description: Question about ASRock AMD motherboards
URL: https://forum.asrock.com/forum_posts.asp?TID=113292
Printed Date: 06 Oct 2025 at 6:40pm
Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com
Topic: Phantom Gaming B850I Lightning Dual GPU
Posted By: Yuns92
Subject: Phantom Gaming B850I Lightning Dual GPU
Date Posted: 11 Aug 2025 at 8:42pm
|
Hello, I'm Yuns92 and new to this forum. Unfortunately, my English isn't perfect, but I hope everyone can understand me. I'm having two strange issues with my new HTPC build: Components: - Case: Fractal Design Ridge (White, PCIe 4.0, Mini-ITX) - PSU: Seasonic FOCUS SGX-750 (750W SFX) - Motherboard: ASRock Phantom Gaming B850I Lightning WiFi - CPU: AMD Ryzen 7 8700G (boxed) - RAM: Klevv Fit V 32GB Kit DDR5-6000 (CL28-36-36-76) - dGPU: Sapphire Pulse Radeon RX 6800 (16GB GDDR6) - CPU Cooler: Thermalright AXP120-X67 White ARGB Note: I delidded the CPU, applied liquid metal for better thermals, and insulated the exposed SMD components on the CPU with nail polish to prevent short circuits. After a fresh Windows 11 install (fully updated), I enabled the EXPO profile in BIOS for RAM overclocking. I have also updated to the latest BIOS version available. My goal: A dual-GPU setup using "lossless scaling" (dGPU renders games, iGPU handles frame generation). Problem 1: When using the motherboard's HDMI output (iGPU), I cannot select 4K@120Hz on my TV. This is unexpected since both the motherboard and 8700G's iGPU support HDMI 2.1. Works flawlessly via the dGPU's HDMI port. Problem 2 (more critical): If my TV is connected to the motherboard (iGPU) and I set the dGPU as the default "High-Performance GPU" in Windows, any game launch causes a full system freeze (games, Task Manager, all apps). A hard reset is required. However: -> Using the iGPU as default (display connected to motherboard) -> games run fine. -> Using the dGPU as default (display connected to dGPU) -> games run fine. Troubleshooting done (no success): - Updated BIOS to the latest version. - BIOS reset to defaults. - Use default speed for RAM. - Set PCIe Gen to 3.0 in BIOS. - Increased iGPU VRAM allocation. - Reinstalled AMD chipset + GPU drivers. I'm out of ideas. Has anyone encountered this or know a solution? |
Replies:
Posted By: Xaltar
Date Posted: 12 Aug 2025 at 4:01am
|
It sounds more like an OS issue. Multiple GPUs have been problematic from the start but they have also fallen out of favor lately. By the sound of it, windows isn't routing the workload and signals properly. If you search "iGPU + dGPU windows issues) you will see quite a lot of people reporting issues. To rule out hardware you can try a gaming focused linux distro like Bazzite or Nobara. If you can get things working right there then the issue is likely down to the OS and drivers. Good luck  ------------- 
|