Hacker News Reader

Comment by oompydoompy74 | Hacker News Reader

I’ve been looking for a DisplayPort to HDMI cable to get around this on our household couch gaming computer. I have been unable to find one sketchy or otherwise that can handle high refresh rate and 4:4:4 color.

View on HN

https://www.club-3d.com/shop/cac-1088-1223 (https://geizhals.eu/club-3d-aktiver-adapter-cac-1088-a331004...)

https://www.club-3d.com/shop/cac-1087-1128 (3m cable version)

DP 1.4 → HDMI 2.1. Apparently they're no longer being manufactured (?? - not sure that's correct), so get one while it's still possible...

[Ed.: accidentally linked another adapter that is the other direction. Added 3m & direct manufacturer links.]

What a road down the memory lane… Club 3D GPUs in the early 2000s

Ty for the links! I’ll look into this.

FWIW, most USB docks are effectively this. DP goes in via USB-C and HDMI comes out the other end.

I bought one from UGREEN on Amazon. I think it's called the 9 in 1. It does 4k@60 with HDR, coming out of SteamOS.

But are there any that don't overheat when you try to funnel dual screens through the USB-C/TB4?

The only setup I have that doesn't is a super minimal one that has a single DP out that feeds a daisy-chain (and a single USB out that feeds a simple hub for low bandwidth peripherals, and a PD in). Unfortunately, most of the screen pairs that I run don't do daisy-chain.

Every other hub I tried eventually got me to give up and connect one of the screens through direct HDMI.

The key is to not use TB4; that's far more energy intensive to handle than DP1.4 alt mode (+ MST for 2 displays). Basically the dock needs to be a little shitty and not have too many features...

But does it support VRR?

I’ve never thought about trying a dock. Thanks!

I usually go for Cable Matters cables, they tend to be of a decent quality and follow the specs well. UGREEN is supposedly a reliable option too, though I cannot personally vouch as I haven't used their cables in particular.

VMM7100 based devices like the Cable Matters 102101 work. Also allegedly CH7218 based adapters. https://gitlab.freedesktop.org/drm/amd/-/issues/4773

Going to be watching this ticket for sure.

According to the article, these adapters generally don't support VRR.

I think the article is honestly a little outdated on this point. The last couple of years the adapter market has caught up pretty well.

The UGREEN 8K@60Hz Display Port to HDMI Adapter I have sitting here supports g-sync (and claims support for freesync).

I mean the article is two days old, so perhaps not that outdated. There also seems to be a difference between G-sync, Freesync, and HDMI VRR.

Why does everybody seem to overlook this?

I'd say because most people don't care about VRR...

People who buy Valve's Steam Machine should care though, because they will get bad frame rates without VRR.

The frame rate won't really be any different, there'll just be a little bit of extra delay until you can actually see the frame that was just rendered, and maybe some barely detectable stutters. Keep in mind we're talking 4K120 or 8K here, the GPU in the Steam Machine is nowhere near fast enough for either of these things. It's likely that there's always some mode with a higher fixed frame rate than what the GPU can calculate, even on Full HD you can probably just do fixed p120 or p144.

VRR is all about smoothness/microstutters, not higher frame rate/performance.

Without VRR you get screen tearing when the frame rate below 60 FPS. (Except if it is locked to 30 FPS.)

Reply on news.ycombinator.com