How to fix WD Black SN850 random read lag in Final Fantasy XV?
Whenever I entered the Insomnia district, the game would hitch for a fraction of a second, which is just jarring when you're playing in 4K. I ran a latency analyzer and found the WD Black SN850 1TB had these weird 4K random read spikes between 15-22ms, meaning the assets weren't hitting the VRAM pool fast enough. My first instinct was to toggle 'High Performance' in the Windows power plan, but while the CPU stayed clocked up, the I/O latency didn't budge. It was a bit of a struggle, but I eventually realized the generic Windows driver was the culprit. I wiped the stock driver and installed the latest official NVMe controller firmware, then disabled Link State Power Management in Device Manager. In CrystalDiskMark, the random read latency dropped from 18-25ms to a much tighter 6-9ms, and the stuttering vanished. I did have a couple of slow boots right after the firmware update, but a quick CMOS clear fixed that. Operating temps are now 44-52℃. The I/O logs confirm the data stream is finally smooth.
