Just a quick thread to show there is no RTC or clock drift issue with Skylake when changing the BCLK at runtime.
Test: Skylake i7 6700K with RTC enabled in Windows 10. Based on the findings described here, we would expect a difference in benchmark result from running 41x100, 40x102.5, and 42x97.6. Specifically, 42x would be approximately 3.4% faster than 41x.
In our test we find that:
40x102.5: 8.977 sec
41x100: 8.983 sec
42x97.6: 8.999 sec
This confirms with the hypothesis that Skylake isn't affected by clock drift.
The real technical reason is that the BCLK frequency is now a separate ICC and is no longer tied to the other clock frequencies.