PlayStation 4 is powered by a GPU that is roughly equal to what PC graphics card?

There is no exact equivalent because Sony worked with AMD to produce a unique APU for the PlayStation 4 that contained a custom Radeon 7970M, which was itself a mobile variant of early 2011’s desktop flagship HD 7970.

Compared to the desktop card, the 7970M ran 125MHz slower, had 12 less GCN cores, half the stream processors as well as less ROPS/texture units, while the PS4’s custom GPU reduced those specs by another 50MHz, 2 GCN cores and other tweaks, not to mention that its RAM is shared between the GPU and CPU.

The full size HD 7970 had 3.79 GFLOPs of compute power, the 7970M dropped that to 2.17 GFLOPs, and the PS4’s GPU cut that again to 1.76 GFLOPs, which is roughly on par with a (then) $250 desktop Radeon HD 7850.

For a more recent PC equivalent, you could take a look at the Radeon R9 280X which we revisited in 2018 and was compared against more modern GPU releases, in the ballpark of a GeForce GTX 1050 which is capable of reasonable 1080p gaming.

Incidentally, the CPU inside the PS4’s APU is comprised of two Jaguar-based quad-core processors (akin to somewhat rare AM1 Athlon SoCs).