I'm experiencing a pair of interesting issues I haven't managed to find documented anywhere else.
1. The entire system stutters when one thread is maxed. For instance, when loading an application or doing something particularly processor intensive in a game: a video on my second monitor will start to stutter and the audio and video will desync. The audio usually freezes and then recovers, and the video will play back at an accelerated rate for a moment to roughly catch up. CPU usage in such a situation will show fairly even usage on most cores, with one core hitting 100%; I've never seen two cores reach 100% in tandem. GPU usage is far below max, and the issue occurs within the entire OS, it's just easiest to notice with a video or music playing.
2. The entire system desyncs from real-world time. This manifests in a few ways, the most obvious being that the system clock will be either slow or fast, often ending up off by multiple minutes within a ~10 real-world minute span. The system usually thinks time is passing faster than it actually is, which results in things like a game reporting 300 APM, when I know from experience that I'm providing 380-400. The exact same action after a restart will show the correct value of ~400. The desync also seems to result in the system freezing on/duplicating actions. For instance: a minute camera adjustment in a game will result in a sudden 120 degree snap.
I'm running a fresh install of Windows 10 64-bit with an up-to-date BIOS, and the issue persists with both stock and overclocked settings on CPU/RAM. My CPU did arrive with a hairline fracture in the IHS, but I assume the silicon is fine if the system is even posting.
Ryzen 5 1600
16GB DDR4 2966Mhz
MSI B350 Gaming Pro Carbon
Nvidia GTX 1070ti
Samsung 860 Evo 500GB SATA SSD