Re:How many kinds of USB-C to USB-C cables are there?
by djsumdog on Monday July 15, 2019 @05:17PM
(#20445374)
DP1.2a should be enough for 60Hz at UHD/2160p. 1.4 is needed for HDR support, 5K, higher refresh rates, etc.
Re:How many kinds of USB-C to USB-C cables are there?
by kllrnohj on Monday July 15, 2019 @06:42PM
(#20445985)
DP 1.2a goes up to 21.60 Gbit/s, and 4k 60hz (which does work fine over 1.2a) needs 12.54 Gbit/s. I'm not sure how the 5Gbit/s and 10Gbit/s USB-C cables fit into this. It's obviously not just based on the cable's "rated" bandwidth, as if it was neither the 5Gbit/s nor 10Gbit/s connection would work at all for display. But it does, so it must not be, so what is it?
Is it 5Gbit/s per twisted pair? That would make sense as displayport uses 4 pairs so 4 * 5 comfortably gets you the 12.54 with plenty left over for regular data. But then it would matter for the 10gbit/s cables if it's talking about superspeed 1x2 (2x5gbit/s) or 2x1 (1x10gbit/s).
Re:How many kinds of USB-C to USB-C cables are there?
by mrb on Monday July 15, 2019 @09:05PM
(#20446685)
«I'm not sure how the 5Gbit/s and 10Gbit/s USB-C cables fit into this.»
A USB3 cable has 4 differential pairs. When in alt mode, all 4 pairs transmit in the same direction, so a 5 Gbit/s cable can transmit 20 Gbit/s.
Here is the answer: if you need DisplayPort 1.0-1.2, a 5 Gbps cable is enough.
If you need DP 1.3-1.4 (where they upped the transfer rate for higher resolution and fps,) you need a 10 Gbps cable.
If you need DP 2.0 (I don't think products are out yet, the standard was finalized last month,) you will need a USB4 20 Gbps cable.