Apple has started to release more orders to AMD for high-end Vega GPUs needed for its upcoming 27-inch iMac Pro all-in-one desktop ahead of its scheduled launch in December.

According to trade publication DigiTimes, Taiwan-based semiconductor assembly and test companies Siliconware Precision Industries and King Yuan Electronics have stepped up 2.5D packaging for these GPUs.

The upcoming iMac Pro will use AMD’s Radeon Pro Vega 56 GPU with 8GB HBM2 video memory or the Radeon Pro Vega 64 with 16GB HBM2 memory.

The Vega GPUs are fabricated by GlobalFoundries on a 14-nanometer process technology.

According to John Ternus, Apple’s Vice President of Hardware Engineering, iMac Pro will be Apple’s fastest and most powerful Mac ever, at least until a rumored modular Mac Pro arrives some time next year.