Comment by stefan_

13 days ago

Displays are still bandwidth killers today, we kept scaling them up with everything else. Today you might have a 4k 30bpp 144hz display and just keeping that fed takes 33Gbit/s purely for scanout, not even composing it.

18 comments

stefan_

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danudey  13 days ago

I have a 4k 60Hz monitor connected to my laptop over one USB-C cable for data and power, but because of bandwidth limitations my options are 4k30 and USB 3.x support or 4k60 and USB 2.0.

I love the monitor, it's sharp and clear and almost kind of HDR a lot of the time, but the fact that it has a bunch of USB 3.0 ports that only get USB 2.0 speeds because I don't want choppy 30Hz gaming is just... weird.

monkeyelite  12 days ago

4k jumped the gun. It’s just too many pixels and too many cycles. And unfortunately was introduced when pixel shaders starting doing more work.

Consequently almost nothing actually renders at 4k. It’s all upscaling - or even worse your display is wired to double up on inputs.

Once we can comfortably get 60 FPS, 1080p, 4x msaa, no upscaling, then let’s revisit this 4k idea.

  • bzzzt  11 days ago

    I didn't have to be '4K', it just should be sharp - Apple was right in 2012 with the 'retina' concept. TV manufacturers doubled the resolution and those panels trickled down to PCs. Games and movies don't need that resolution, but it helps text readability tremendously. And as a bonus you can skip all that 'cleartype' nonsense and other readability hacks that often don't work right.

  • account42  12 days ago

    WTF are you talking about, 60 FPS for 4K isn't even that challenging for reasonably optimized applications. Just requires something better than a bargain bin GPU. And 120+ FPS is already the new standard for displays.

    • monkeyelite  12 days ago

      I’m telling you that even if those are the numbers on paper, the software and hardware are using tricks to achieve it which lower the overall quality.

      So yes you get 4k pixels lit up on your display, but is it actually a better image?

      And yes there may be high end hardware which can handle it, but the sw still made design choices for everyone else.

      There are also image algorithms which are not as amenable to GPUs which are now impossible to compute effectively.

bobmcnamara  13 days ago

We see this in embedded systems all the time too.

It doesn't help if your crossbar memory interconnect only has static priorities.

hulitu  12 days ago

And marketing said, when LCDs were pushing CRT out of the market, that you don't need to send the whole image to change a pixel on an LCD, you can change only that pixel.

  • p_l  12 days ago

    except DVI is essentially VGA without Digital-to-Analog part, and original HDMI is DVI with encryption, some predefined "must have" timings, and extra data stuffed into empty spaces of blasting a signal designed for CRT.

    I think partial refresh capability only came with some optional extensions to DisplayPort.

    • rasz  12 days ago

      Im not even sure if partial refresh is a thing outside of e-Paper displays. The best we can do on DP is Variable Refresh going all the way down to Panel Self-Refresh.