Question FCLK and MCLK BIOS Settings and Readout Confusion

[kawzman]

In the BIOS, I’m using XMP 2.0 profile 1 which is DDR4-3600 16-19-19-39 1.35V. If I leave the infinity fabric freq setting at auto, CPU-Z reports my NB freq at 899.8 MHz and DRAM freq at 1799.6 MHz. The BIOS description for the FLCK is that when set to auto FLCK will equal MCLK. So shouldn’t the reported NB freq also be 1799.6 MHz? At 899.9 MHz, that’s a 1:2 ratio and not 1:1. I temporarily manually changing the FCLK to 1800 MHz and there were no apparent issues after doing so. Thoughts? Thanks for the support as always!

AMD Ryzen 9 3900X (OC set to auto)
G.SKILL Trident Z Neo 32GB F4-3600C16D-32GTZNC (2x16GB dual channel)
ASRock X570 Taichi

 

[kawzman]

Here's a screen capture from CPU-Z that visualizes what I'm describing.

 

[alexbirdie0]

I did the same, set FLCK to 1800 and everything was 1:1 and OK.