This was posted in the R5,7,9 3000 series thread as well...
A word on boosting behavior of a R9 3900x in an Asus TUF B350M plus gaming:
1.Under lightly threaded loads-
A. One to two cores will generally be boosted to 4.525-4.575ghz, of coarse the core being boosted isn't always the same, it switches as the load switches and generally this happens every few seconds.
B. Occasionally one core will hit 4.6-4.65ghz, but this it is somewhat rare and only seems to happen in short bursts.
C. High single core boosts seem to be limited to the first chiplet only (cores 0-5 as listed in HWiNFO64)
D. The second chiplets cores only boost to 4.375ghz max
E. While at stock this is the most interesting section, with PBO custom settings this seems unaffected almost entirely... only difference I see is in duration not clock speeds.
2. Under moderately threaded/moderate loads
A. Much less interesting than the single core, but still seems to be pretty spot on as to which cores it boosts hitting speeds up to 4.5ghz on hardest hit cores
B. Cores that are carrying lesser loads, but still loaded moderately usually hit 4.3-4.4ghz range and will be spread out across chiplets occasionally.
C. Gaming loads generally don't count as moderately threaded loads on this chip and tend to run on the first chiplet with higher boosts, however some
more heavily threaded games will cross chiplets and behave the same as other moderate loads.
D: PBO with custom settings allow more loads to hit 4.5ghz mark here with generally up to 8 threads as long as they land on the first chiplet (they usually do)
3. Under heavily threaded/heavy work loads:
A. Very boring, generally depending on power limits and heat.
B. Boost clocks for me are generally from 4.075ghz with the heaviest loads to 4.25ghz with lighter all core loads. Example: 4.125ghz in cinebench R15
C. After setting PBO with custom settings cinebench and similar loads holds around 4.225ghz with very few loads pulling it down to 4.15 now
In conclusion: Boost seems to be pretty much as expected for this chip even though it's in a cheap board... even while just typing this up I saw one core hit 4.625. Would I recommend buying a B350 board for one of these.... no, but if you have one already I would say don't bother buying a new board unless you want/need the newer features... otherwise your performance looks to be unaffected. Hope this helps someone and isn't too repetitive of other posts.
Edit: added PBO results
Offical Ryzen 9 3900x Owner!
ASUS B350M-tuf plus gaming
Gigabyte 5700XT gaming OC
Gskill FlareX 3200 cas 14
Samsung 970 evo
Red Dragon retro something something blue mechanical something
home scratch with a huge sub woofer.
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Last edited by Minotaurtoo; 03-14-2020 at 07:09 AM.