Do the PS5 and Xbox Series X need an HDMI 2.1 cable for 4K 120 Hz?
AnswerYes
Yes, an Ultra High Speed HDMI cable (the cable grade for HDMI 2.1). Both consoles include one, so use it. 4K 120 Hz in 10-bit HDR needs about 32 Gbps, which only an HDMI 2.1 FRL link can carry. The TV input must also be HDMI 2.1 with 4K 120 support. On many TVs that's only one or two of the inputs.
4K 120 Hz, 10-bit HDR
| Link | Needs | Has | Result |
|---|---|---|---|
| HDMI 2.0TV timing | 35.64 Gbps | 14.40 Gbps | Too much |
| HDMI 2.1 40G | 32.27 Gbps | 35.56 Gbps | Fits |
| HDMI 2.1 48G | 32.27 Gbps | 42.67 Gbps | Fits |
How the numbers are worked out
Reduced-blanking timing (VESA CVT-R2)
3840×2160 active → 3920 × 2287 total pixels per frame
3920 × 2287 × 120 Hz = 1075.80 MHz pixel clock
1075.80 MHz × 30.0 bits per pixel = 32.27 Gbps
10-bit colour, full RGB/4:4:4: 3 × 10 = 30.0 bits per pixel.
HDMI 1.4/2.0, standard TV timing (CTA-861)
3840×2160 active → 4400 × 2250 total pixels per frame
4400 × 2250 × 120 Hz = 1188.00 MHz pixel clock
1188.00 MHz × 30.0 bits per pixel = 35.64 Gbps
10-bit colour, full RGB/4:4:4: 3 × 10 = 30.0 bits per pixel.
"Has" is the link's usable rate after line coding. DSC is modelled as up to 3:1 compression. Full method.
4K 120 Hz, 10-bit HDR, 4:2:0
| Link | Needs | Has | Result |
|---|---|---|---|
| HDMI 2.0TV timing | 17.82 Gbps | 14.40 Gbps | Too much |
If the TV menu offers 4K 120 only on HDMI 3 or 4, that's the HDMI 2.1 input. If 120 Hz disappears when you use a longer cable, the cable isn't holding 40 Gbps. Certified Ultra High Speed cables come with a scannable label.