PlayStation 5 achieves a lower maximum bandwidth of 32Gbit / s via HDMI 2.1
The PlayStation 5 currently appears to support a maximum bandwidth of 32Gbit / s via the HDMI 2.1 standard. That is lower than the 40 or 48Gbit / s required to display 4k images at 120fps without chroma subsampling.
The observation of a bandwidth of 32Gbit / s was previously reported by users on various forums, such as that of NeoGaf , and television reviewer Vincent Teoh has now confirmed this on the basis of a retrievable game information screen of the LG CX-OLED TV. There it is indicated that there are 4 lanes with 8Gbit / s, and therefore a total of 32Gbit / s.
This is also evident from the PlayStation 5’s settings menu, which lists all supported refresh rates in Hz, namely 24, 25, 30, 50, 60 and 120Hz. It is striking that ‘YUV422’ is mentioned with the 120Hz option. That means 4: 2: 2 chroma subsampling and therefore a somewhat lower color resolution to save bandwidth.
The combination of a 4k resolution with 120fps and 4: 2: 2 chroma subsampling means that 32Gbit / s of bandwidth is required. If no reduced color resolution would have been used, in short 4k, 120fps and 4: 4: 4, the bandwidth would still be 32Gbit / s at an 8bit color depth, but then there is no HDR. At 4k, 120fps, 4: 4: 4 chroma subsampling and 10bit color depth, the bandwidth is 40Gbit / s.
The chipset in the PlayStation 5 should just be able to support 40 or 48Gbit / s. It is not clear whether this current maximum of 32Gbit / s is a limitation in the software or the hardware. It is therefore not possible to say with certainty whether this limitation can be removed by means of a future firmware update.
The application of 4: 2: 2 chroma subsampling means that the colors may look a bit fainter compared to 4: 4: 4. Image artefacts may also be visible at 4: 2: 2. The idea here is that color resolution is sacrificed and thus color information is lost, but that is unnoticeable in most natural images, because the resolution of the brightness signal is preserved.
This limitation to 32Gbit / s is only a factor for players who combine their PS5 with an HDMI 2.1 screen. The vast majority of users will still have a television with HDMI 2.0, where the bandwidth is a maximum of 18Gbit / s. For these televisions, 4k, 60Hz with 4: 2: 2 is the maximum achievable, based on 10bit color depth.
The Xbox Series X and S have a maximum bandwidth of 40Gbit / s and therefore do not apply a reduced color resolution. Incidentally, there is also a limitation with the Xbox Series X. If the refresh rate is manually set to 60Hz in the graphics settings of this console, the console will switch to the HDMI 2.0 specification and with a corresponding maximum of 18Gbit / s. That means that 4k, 60Hz, 4: 4: 4 and a 10bit color depth is not possible, because it requires 20Gbit / s. Thus it falls back to 4k, 60Hz, 4: 2: 2 and 10bit. By the way, this can be prevented by simply leaving the setting in the Xbox at 120Hz when using an HDMI 2.1 television, and optionally opting for 60Hz in a game. At that point, the console just stays off the HDMI 2.