DisplayPort 1.2 cannot even do 5k at 60Hz at 10 bits per channel. You might be thinking about DisplayPort 2.0, which is not yet widely supported in video cards or monitors, and even then it needs the (essentially non-existent) UHBR 20 data rate to get to 120Hz.

HDMI 2.1 does support 5K@120Hz@10bpc but requires DSC as you say, which is not very commonly found either.

(Note that unlike what a sibling comment states, DSC is lossy. Some argue that the less is not noticeable to the human eye, but not everyone agrees)

> HDMI 2.1 does support 5K@120Hz@10bpc but requires DSC as you say, which is not very commonly found either.

Not very commonly found on what? Nvidia & AMD have been shipping DSC for ~2 generations now (so almost anything within the last 4 years has it)

It's not commonly found on monitors. DSC is included starting with DisplayPort 1.4, and a good portion of monitors even today still ship with DP 1.2

Nvidia and AMD have not been shipping DSC with HDMI simply because HDMI included DSC starting with HDMI 2.1, which only the current generation of graphic cards and very few monitors support.

What’s DSC?

Display Stream Compression, a lossy compression algorithm optimized for the specific use case of device-display transfers (i.e. relatively low compression ratio == very high quality that's claimed to imperceptible even if it can't run lossless, not needing to work on full frames for speed/sub-frame latency, ...)

I didn't know either. DSC is Display Stream Compression, and has been part of the spec since 1.4. According to Wikipedia [0],

> DSC is a compression algorithm that reduces the size of the data stream by up to a 3:1 ratio.... Using DSC with HBR3 transmission rates, DisplayPort 1.4 can support 8K UHD (7680 × 4320) at 60 Hz or 4K UHD (3840 × 2160) at 120 Hz

0: https://en.wikipedia.org/wiki/DisplayPort#1.4