A
Which carrier for the S5 are you asking about? Many versions have already had their Marshmallow update released.



Hi STARGATE!
Unlike AT&T or Verizon who issue their own firmware updates, Sprint is updated directly from Samsung and your Product Code, SPR, dictates whether or not you are updated. Install, free from the Play Store, Phone INFO ★Samsung★ and check the under CSC CODE - Product Code: and you should see that the last 3 digits read SPR.
I'm seeing that this update is offered when I start up Kies 3 and connect the phone to the USB port:
PDA:OK4 / CSC:OK4 / PHONE:OK4 (XAS)
...yet Kies doesn't tell me exactly what this update is. Is it Marshmallow, or is it only the incremental patch from several months ago? I'm thinking it's the latter because I remember the sequence OK4. OTOH, if memory serves, when I saw the incremental update on Kies it did show the entire lengthy string of characters, of which the substring "OG1" was only a small part.
Release OK4 on the model, G900P, on Product Code XAS, is for Android 5.0, Lollipop...
Model SM-G900P
Model name GALAXY S5
Country Unknown
Version Android 5.0
Changelist 4781399
Build date Tue, 10 Nov 2015 07:37:35 +0000
Product code XAS
PDA G900PVPU3BOK4
CSC G900PSPT3BOK4
