Zwift doesn't open when connected to 4k TV

I’ve just bought a Dell G7 gaming laptop with an Nvidia GeForce RTX 2070 GPU; when connected to an old 50" TV I can get 140FPS (!) at 1080 resolution. But when I connect to our 65" 4K TV (via a 4K DisplayPort-to-HDMI cable) Zwift doesn’t open? I can see the ZwiftApp and ZwiftLauncher threads running in Task Manager, but nothing is “open” and running …

If I launch Zwift before connecting to the TV I can move Zwift onto the 4K TV / monitor and it works, but it max’s out at 30.0 FPS and is actually only generating 1080 resolution and not 4K (via ZwiftAnalyser).

Any thoughts on how to get 4K running properly?

Phil, it is a very well known fact that it is hard to make HDMI work with 4k, or similar to 4K (many computer monitors have different proportions of the screen dimensions than 16:9 of 4k TVs and the number of pixels may be similar, but not exactly 4k) at a frame rate over 30 fps, if at all. Unfortunately, most “4k” cables sold on Chinazon (sorry, typo, I meant, Amazon) are Chinese junk not certified to do what they are claimed to do. On top of that, in general, high resolution video at high frame rate requires DP or USB-C (and these cables which really work are also hard to find and they cost!). If your TV supports input from DP or USB-C, try a certified DP or USB-C cable - it might help. The fact that your TV maxes out at 1080p and 30fps is a direct indication that this is all that your cable can support, regardless of what the vendor stated. When computer talks to a monitor, it automatically adjusts frame rate and resolution to what can be supported (allowed by the bandwidth of the cable).

Zwift also initially runs a test of what the graphics/monitor can support. It probably runs into a problem and shuts down because it cannot figure out what resolution can be supported. I would start with blaming it on a shitty cable.

For 60 FPS in 4k, you need a Certified HDMI 2.0 cable (or higher, HDMI 2.1). It will not be cheap (be ready for something along the lines of $50+) and it will be very hard to find on Chinazon!

Your laptop probably has a USB-C port which doubles up as a charging port, and the odds are that it could be the most capable port on your computer when it comes to graphics. I think Dell also calls it a “Thunderbolt” port, which is for practical purposes, a high level version of DP in USB-C form factor. Your mini-DP port might actually not designed to support full 4k and may be designed for a secondary monitor. It can get tricky with Dell laptops ports (don’t ask me how I know :slight_smile: ). It is so much easier with full size GPU cards used in desktops!

Sorry, as I think while I type, I would not bet on your laptop supporting 4k through HDMI port, and as I said, it might not support it through mini-DP or DP. It might only USB-C that has its capability.

BTW, high quality USB-C cables (fully certified) are equally difficult to find. Low end just switch to lower resolution or lower frame rate.

My apologies about multiple edits (if your got several notifications)

Andrei - thank you so much for getting back to me; seriously, I really appreciate it.

I understand what you mean about how a crappy quality cable could be limiting the resolution/frame rate; but it cost $65 and was bought from a national chain technology store; the box said 4k @ 60Hz … but it would seem it might be limiting to 30FPS … which wouldn’t be absolutely terrible compared to 60FPS, but only getting 1080 instead of 4k is a big difference.

This is the one I got: alogic-ultra-mini-displayport-1-4-to-hdmi-2-0-cable-4k-60hz-active

When I log into the Nvidia control settings; it says that the HDMI, Mini DisplayPort and USB-C are all directly coming from the graphics card … and my (poor) research was that DP 1.4 should be a better option than HDMI 2.0a/b - which is why I opted for that cable. The Nvida settings say it’s connected at full 4k resolution at 60Hz, and I can watch videos in 4k resolution via the laptop on the TV in 4k. You think I should still try a USB-C to HDMI cable instead? Doesn’t the HDMI on the other end going into the TV providing a bottleneck anyway??

Which leads me to think it’s potentially more likely a Zwift setting thing rather than a laptop capability (and also hopefully cable quality) thing? Reading through some posts is sounds like Zwift can be a little finnicky sometimes with some of the settings … perhaps I just need to muck around a bit more to try and get something working. e.g. I had overloaded the foliage setting by 500%! But I’ve reverted this back to default Ultra setttings now … :wink:

Hi Phil, may I suggest a simple test? You can always use your TV as an internal monitor. Windows allow you to connect two monitors to your computer. It will take 5 mins to do the following:

  1. Connect TV to your laptop using your cable. Boot up your laptop. Most likely, your WIndows screen will be duplicated on both screens in 1080p.
  2. Right-click on desktop and pick in the content menu “Display settings”. Scroll down to Multiple Displays.
  3. You will have options to either duplicate your primary display or extend your primary display. Pick the extend option. This will enable you to set resolution of each monitor individually (and display different contents on each).
  4. See if you can set your external monitor resolution to 4k (3840x216).
  5. In Advanced Display Settings you will be able to pick each of your two monitors (the Laptop’s screen and TV). Your computer will show resolution and refresh rate on each of two screens.

Do it all just running windows, without Zwift.

If you find that you can run your TV as a monitor at 4k at 60 Hz, and you will indeed see that resolution of your TV is much higher than of your laptop screen (if you drag a window from laptop to TV, it will take much lesser fraction of the screen), your cable is fine, it supports 4k at 60 Hz, and the task of figuring out what Zwift can and cannot do will be your next step.

If you find that you can only run your TV at 1080p, this means your cable is not performing up to your expectations and to the manufacturer specs (just in case, check your TV manual - if all HDMI ports support at least HDMI 2.0 and support 4k, 60 Hz. You never know :slight_smile: You wrote that your Dell laptop can support 4k 60 Hz on mini DP, so that part should be OK.)

  1. Zwift renders in 4K with the right hardware. If it wasn’t, how would it be possible to generate a 4K resolution screenshot?
  2. You absolutely don’t need an expensive HDMI cable, that’s utter cobblers. Anything 2.0 will do, and I’d suggest that over the DP/HDMI adapter you have.
  3. Doesn’t sound like you’ve actually changed the game resolution setting to 4K, if Zwiftalizer is still showing 1080p.
  4. If you’d set the foliage to 500% then you’ll have been massively increasing the load on your GPU and thus decreasing the frame rate. With standard Nvidia settings this would see you drop and be capped at 30fps due to vsync anyway. This can be corrected.
  5. You may need to check the game modes your TV has. If the ports at both ends are 2160p60 capable and the cable is too, there’s no reason why you can’t run Zwift in full 4K.

Hi Dave, Andrei - apologies for the delay getting back to you (I’ve been away for the last 10 days) and thanks again to both of you for the advice.

I can confirm that I can get Zwift to run in 4K (same cable); but I had to “force” it … I updated the Ultra config file to specify 4K resolution, and I also updated the prefs.xml file with the following (which I assume is the same as selecting it from the drop down menu in settings mid-game, which as you pointed out Dave I had not done, and the “Ultra” option does now appear when I use the 4K TV):

So after I load Zwift and then drag the window onto my second monitor (i.e. the 4K TV) and expand the window; it does run in 4K and Zwiftaliser confirms it. I can also get the FPS up over 30 via changing the Vsync settings, it sits at about 55~60FPS (even with foliage at 500% … which is obviously unecessary, I’m just mucking around).

Interesting though; Zwift will not “open” (load?) if the TV is connected first … I have to start Zwift and then connect the TV. Weird … but not a serious issue, albeit a little annoying.

But I’m up and running!

Thanks again.


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Phil - Thank you very much for sharing! Congratulations!