The PS4 had GDDR5 RAM for main memory, which no one else (including PCs) was doing at the time. According to Cerny (at the time), a single pool of fast memory

The PS4 had GDDR5 RAM for main memory, which no one else (including PCs) was doing at the time. According to Cerny (at the time), a single pool of fast memory was the #1 thing Sony's 3rd party devs were begging for.