Memtest failing on brand new 13900KF but doesnt fail on 13600KF with same bios settings

Understanding Memory Compatibility and Stability: Troubleshooting MemTest Failures on New Intel 13th Gen CPUs

In the evolving landscape of high-performance computing, ensuring system stability is paramount—especially when assembling a new build or upgrading components. Recently, a user encountered a perplexing issue: MemTest86, a widely used memory testing tool, failed on a brand-new Intel Core i9-13900KF system but passed on a previous or different CPU setup, such as a 13600KF, under similar BIOS configurations. This situation prompts a deeper exploration of potential causes and effective troubleshooting strategies.

System Overview

The affected system features a Z690 motherboard with the latest BIOS update, aimed at maintaining optimal compatibility with Intel’s 13th generation processors. The user’s memory test configuration involved enabling the XMP profile, which sets DDR4 memory to a specified frequency—in this case, 5600 MT/s—while keeping other BIOS settings at default. Additionally, Resizable BAR (Re-Size BAR) was enabled to optimize graphics memory access, a common setting for gaming and high-performance tasks.

Key Observations

Successful MemTest on 13600KF: The memory passed extensive testing without errors when using the 13600KF processor.
Failures on 13900KF: The same memory, with identical BIOS settings, produced errors during MemTest86 on the 13900KF system.
Memory Compatibility Confirmed: The RAM has been verified to work correctly with other systems, including a Ryzen 7 7700X, indicating that the hardware itself is likely stable.

Possible Causes and Considerations

Processor Microcode and Compatibility

Newer CPUs often require updated BIOS versions to incorporate the latest microcode, which can affect memory compatibility and stability. Ensuring your motherboard BIOS is fully updated is essential. Even if you are on the latest BIOS, sometimes specific microcode updates for the 13900KF can influence memory behavior.

Memory Timings and Voltage Settings

Although the BIOS was left at default aside from the XMP profile, subtle differences in CPU memory controller behavior between different CPU models can cause stability issues. Stock profiles are a good starting point, but some CPUs may require manual adjustments to timings or voltage to achieve stability.