Ferrari has entrusted its latest-spec power unit to customer teams Alfa Romeo and Haas, while the Scuderia will likely run the new engine at Monza.
Both Kevin Magnussen and Romain Grosjean are running the new unit at Spa while only Antonio Giovinazzi will have the updated hardware at Alfa Romeo.
All three drivers remain clear of any grid penalties at Spa following the change, and so will Sebastian Vettel and Charles Leclerc at Monza next week.
But Kimi Raikkonen's switch at the Italian Grand Prix will lead to a grid demotion as the Finn has already reached the limit of each PU element.
Ferrari's decision to supply its latest engine to its customers teams means that all manufacturers are running updated units at Spa.
Renault's Nico Hulkenberg and Daniel Ricciardo, as well as McLaren's Carlos Sainz, are all set for a five-spot grid drop following their adoption of the French manufacturer's Spec-C engine.
Honda-powered drivers with updated engines Alex Albon and Dany Kvyat, as well as Mercedes-powered Lance Stroll will line up at the back of the grid following multiple engine changes.