When others say it has a second GPU. It actually one GPU that has both the standard PS4 GPU/PS4 Pro GPU setup, it has the ability of been able too turn one or the other off, so it can mimic the stanard PS4 or function as the PS4 Pro

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Instead of using an entirely new GPU, Cerny said the PS4 Pro is using a "double-sized one." In effect, the new console has a second, identical GPU configured next to the original, with a 14 percent boost in frequency to 911MHz, which more than doubles the processing power of the Pro. While the standard PS4 produces 1.8 teraflops, the PS4 Pro achieves 4.2 teraflops.