3900x max boost clock behavior

BroliviaWilde · July 30, 2019

Questions about 3900x max boost clock behavior

Maybe this has already been answered and I've just not seen it yet, not sure but ...

What I've observed with my own 3900x is the following:

chiplett 1 - various cores at various times will reach 4.6 ~ 4.65 max boost clocks - usually the same 3 cores will reach 4.65, hte others 4.6 or 4.625

chiplett 2 - various cores at various times will reach 4.35 ~ 4.425 max boost clocks at various times - although on this one i've only observed 2 different cores ever reaching 4.425 at 3 different times)

After researching an issue with the bios of my mobo and RAM speeds, I noticed that other people were reporting the same max boost clock behaviour - specifically that any cores that reach 4.6 or higher will always be on one chiplett, and all cores on the other chiplett will reach max boost clocks as noted above. It isn't like some cores from each chiplett will reach 4.6, that isn't the case, it's consistently where the only cores that reach 4.6 are always on one chiplett, and the cores in the other chiplett never reaches it and are a bit below that and look like a 3600x. I've even seen some reviewers show the camera pan across their monitor and where they show HWinfo and I can see the same behaviour.

During troubleshooting bios issue with RAM speed, i've changed bios and power plans, and still same behaviour. And if you want to knw what changes i've made on my system? x470 taichi on bios 3.4, updated to 3.5 and rolled it back to 3.4. Otherwise, left bios with all settings seen the same behaviour, same with turning xmp up from default to 2800. I know, this shouldn't affect cpu max boost clocks, but just wanted to illustrate what I've changed, even if it might seem insignificant.

ok now time to put on a <tin foil hat>

is this behaviour a result of AMD matching a higher binned 6 core chiplett with a 'regular' 6 core chiplett in order to reach the $500 launch price?

Are there 3900x's that have cores on each chiplett that reach 4.6 and I just haven't seen it yet?

is this behaviour a result of some kind of power management limit and this setup was easiest and least complicated way to do it?

If you have answers, post the links, i'm genuinely curious