I'm confused, how is COU speed tied to memory? AFAIK, memory is tied to CPU base speed which is almost always 100 MHz. The CPU then just scales it's own multiplier.
Northbridge frequency (as shown by CPU-Z) is correlated to CPU speed in my experiments. It's not one to one, but NB frequency definitely varies by a factor of two depending on CPU load.
What exact mechanism controls this is not clear to me (and I'm actually not sure if it's clear to anyone outside of Intel - the one paper [0] I found at the time was based on reverse engineering experiments). Nevertheless, CPU clock speed definitely affects Northbridge speed, as proven by the latter increasing from spinning a thread that never touches memory.
> The results [...] indicate that uncore frequencies – in addition to EPB and stall cycles – depend on the core frequency of the fastest active core on the system.
(That conclusion is fully in line with my own observations.)
What exact mechanism controls this is not clear to me (and I'm actually not sure if it's clear to anyone outside of Intel - the one paper [0] I found at the time was based on reverse engineering experiments). Nevertheless, CPU clock speed definitely affects Northbridge speed, as proven by the latter increasing from spinning a thread that never touches memory.
[0]: https://tu-dresden.de/zih/forschung/ressourcen/dateien/proje...
See section V.A:
> The results [...] indicate that uncore frequencies – in addition to EPB and stall cycles – depend on the core frequency of the fastest active core on the system.
(That conclusion is fully in line with my own observations.)
Also see the corresponding patent linked in the paper: https://patents.google.com/patent/WO2013137862A1/en