Optimizing PCIe stability on Biostar B550MH for AC Valhalla
Whenever the massive architecture of Valhalla's towns loaded in, I'd get these tiny, annoying hitches that made me obsessed with fixing them. It turns out the PCIe 4.0 signal on the Biostar B550MH has a 2-5ms sync drift with certain GPUs, causing the VRAM bandwidth to swing wildly between 15GB/s and 30GB/s. I first tried 'Low Latency Mode' in the driver, but that just added screen tearing without fixing the root cause—complete waste of time. I went into the BIOS, forced the PCIe link speed to Gen4, and flashed the latest AMD chipset drivers. In RTSS, the frame times tightened from 18-35ms to a much smoother 12-16ms. I did have a few random reboots after the first Gen4 lock, but bumping the memory voltage to 1.36V finally stopped the instability. Board temps are now sitting at 52-60℃. Comparing the bandwidth curves before and after, the difference is night and day, though the board still runs a bit warm.
