Some interesting facts about AMD’s Renoir APUs have surfaced during the company’s HotChips presentation. Turns out that Zen 2 based APUs were originally planned to top out at six cores, rather than the eight. However, TSMC’s super-efficient 7nm node and the optimized Vega graphics allowed the design team to pack up to 8 cores quite comfortably.
We started by thinking that we would bring in six cores and then, as we were analyzing the P/F curves, that with some careful management of SoC power, we should be able to fit eight cores.Sonu Arora, AMD
This explains two questions many of us had. Firstly, one of the reasons AMD opted for Vega rather Navi with Renoir and possibly again with Cezanne is that the GPU is highly optimized for APUs. Clock speeds as high as 2.1GHz, all the while keeping the power budget under the 25W mark would have been nearly impossible with RDNA.
Second, Renoir was built from the ground up, rather than being a derivative of Matisse, explaining the lower cache size, better memory controllers, better overclocking potential and lack of PCIe 4.0. Many enthusiasts were disappointed over this, but considering that power efficiency is one of the primary concerns with mobile devices, AMD definitely made the right choice.