Troubleshooting Boot Failures on MSI B550 Tomahawk MAX WiFi with GTX 970 and 10G NIC
Building a stable and functional server or workstation around latest hardware components often involves overcoming compatibility challenges. Recently, users have reported specific issues when configuring an MSI MAG B550 Tomahawk MAX WiFi motherboard with multiple PCIe devices, notably a GTX 970 graphics card and a high-speed 10G network interface card (NIC). This article explores these challenges, examines potential causes, and offers guidance for anyone facing similar hardware configurations.
System Overview
The described hardware setup includes:
- CPU: AMD Ryzen 9 3900X
- Motherboard: MSI MAG B550 Tomahawk MAX WiFi (with latest BIOS update)
- Memory: 32GB DDR4 RAM
- Graphics Card: NVIDIA GTX 970
- Network Card: PCIe x8 Intel 10G NIC (installed in second x16 slot)
- Case: Fractal Define 7 XL
- Power Supply: Corsair RM1000e (modular)
- Operating System: Unraid
The Core Issue
The primary problem manifests during system boot procedures:
- With only the GTX 970 installed in the top PCIe slot (PCI_E1), the system boots successfully.
- Introducing the 10G NIC into the second full-length PCIe x16 slot (PCI_E3) results in failure to POST, with the motherboard halting on a red VGA LED indicating display output issues.
- Removing the NIC restores normal boot behavior.
- Notably, the smaller PCIe x1 slot (PCI_E4) cannot accommodate the NIC due to physical size constraints.
What Has Been Tried?
The user experimented with a variety of BIOS and hardware configurations, including:
- Forcing PCIe slot to Gen3 mode instead of Auto
- Enabling the Above 4G Decoding setting
- Disabling Resizable BAR
- Toggling Compatibility Support Module (CSM) on and off
- Updating the motherboard BIOS to the latest version
- Re-verifying physical seating and power connections
- Testing boot with only the NIC (GPU removed), which POSTs successfully, confirming the NIC’s functionality
Possible Causes and Underlying Factors
This issue hints at PCIe lane allocation conflicts or hardware limitations inherent to B550 chipsets:
- Lane Allocation Constraints: The B550 platform’s PCIe lane mapping, particularly in the
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