Comparing newly listed Z370 models with their Z270 versions, ASRock apparently upgraded most of their VRM configurations (and components) on non-flagship models, while ASUS/Gigabyte/MSI kept the last gen VRM configurations. Here are the relevant ASRock models:
- Fatal1ty Z370 Gaming K6
- Z370 Extreme4
- Z370 Killer SLI
- Z370 Pro4
- Z370M Pro4
- Fatal1ty Z370 Gaming-ITX/ac
Z370M Pro4 seems doubled the 4 vcore vrm phases of Z270M Pro4 to 4 x 2 configuration. Fatal1ty Z370 Gaming-ITX/ac somehow has one less vcore phase (5) than Fatal1ty Z270 Gaming-ITX/ac (6). The other 4 models each has 2 more phases than its Z270 ancestor. According to the LGA1151 VRM list from hardwareluxx.de, corresponding Z270 mobos share the same 3 x 2 configuration of vcore VRM phases. So now these Z370 mobos have 4 real phases on vcore.
Is 4 real phases the baseline requirement of CFL 6-core? It's not difficult to filter the other Z270 model in the VRM list with 3 real vcore phases: Biostar Z270GT6. Turns out that Biostar Z370GT6 Ver. 5.x did have 2 more phases on its vcore vrm.
Now all listed Z370 mobos have 4+ real VRM phases to support CFL 6-core (and possible 8-core icelake?) unlocked CPUs.
from top scoring links : multi https://www.reddit.com/r/hardware/comments/73hukd/asrock_biostar_changed_power_delivery_design_on/