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No signal on 4k TV connected to computer via HDMI


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#1 futuretrackstar

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Posted 02 December 2017 - 08:54 AM

Hello all,

 

  I recently purchased a Vizio E43-E2 4k TV. I first purchased the TV with a 30 foot HDMI cable and connected it to one of my computer's graphics card's ports. My card is an ASUS GeForce GTX 1060 6GB. My other computer components are all quite modern, as I built this PC about 1 year ago. With this 30 foot HDMI cable, the signal was displayed from my computer to the TV; everything worked just fine. However, the HDMI cable wasn't quite long enough, as it ran through the middle of my living room.

 

  I eventually went back to the place where I purchased the TV (Microcenter), and returned the 30 foot HDMI cable for a 12 m (about 39 feet) HDMI cable, which is long enough. The manufacturer of the new HDMI is not the same as that of the cable that I returned, but they both are 4k ready HDMI cables. When I arrived home and connected my TV to my computer, no signal could be displayed on my TV from the computer. No matter how many display options I tried on Nvidia's control panel, no matter what order I powered my devices on and off, no matter which ports I connected my cables, nothing has been able to get a 4k signal to my TV. I was able to get a 1080p signal to display on my TV, however.

 

  Sounds like the HDMI cable that I purchased was advertised falsely, right? Well, I also connected the HDMI cable to my 4-year-old laptop, which has integrated Intel graphics processing. My laptop displayed a 4k signal (3840 x 2160) at 30Hz to my TV on the first try. My conclusion was that the HDMI cable is fine, and the TV is fine... something must be wrong on my desktop computer.

 

  I called Nvidia for support. The tech support representative had me try several different things, many of which I had already tried. Nothing that he recommended could get a 4k signal to display from my computer. I have since been receiving suggestions from Nvidia via email, every day, with troubleshooting suggestions. This support has not been helpful. Their most recent suggestion was to take a Screen Capture on my PC and send it to them (the screen capture shows my desktop on my computer monitor adjacent to my desktop on my 4k TV, but of course, no desktop actually displayed on my 4k TV). They also suggested I try changing the aspect ratio on my TV's menu (which did nothing to get a signal accross, obviously), and also suggested I check that the firmware on my TV is up-to-date. The firmware is, and has been, up-to-date.

 

  So, it's been a week now that my computer has been connected to my TV, but I can't actually enjoy it. Yes, the TV's built in SmartCast feature works fine, so I can still cast YouTube from my iPhone, and I can still go on Amazon or Netflix and watch movies with those apps. But, of course, I should be able display a 4k signal from my computer. Worked just fine before I exchanged the HDMI cable, so it should work now.

 

  Thank you for taking the time to read this. Do you have any ideas, or suggestions?

 

Regards,

Andrew



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#2 mjd420nova

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Posted 02 December 2017 - 06:17 PM

Visio has a port checker that runs on power up.  Sometimes the display will not come up unless you restart the TV.


Edited by mjd420nova, 02 December 2017 - 06:17 PM.


#3 mightywiz

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Posted 04 December 2017 - 02:22 PM

did you test with a short hdmi cord using a dvd player or something? just to make sure the port is working?

 

if it does work a short cable then your long cable is going to be your issue. hdmi over 25ft can start causing issues unless you use a repeater/signal booster.



#4 jonuk76

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Posted 04 December 2017 - 03:24 PM

I'd also think the length is the problem. Unboosted signals become very dicey at those sort of lengths. Plus probably the fact that the GTX 1060 card has an HDMI 2.0b output (18 Gb per second, supports 4k @ 60 hz) which I'd theorise will tolerate less signal degradation than HDMI 1.4 (10.2 Gb/s, supports 4K @ 30 hz), because it's trying to connect at nearly twice the data rate.  It may explain how the laptop with integrated graphics (HDMI 1.3/1.4) works but not the GTX 1060.  

 

Worth a read I think - http://www.bluejeanscable.com/articles/how-long-can-hdmi-run.htm

 

It might be that a active cable or booster is needed.  I'm not sure which type will be best.  Looking around I can see potential problems, for example Startech's booster will only guarantee up to 30 ft (with 2 x 15 ft cables) with their booster for HDMI 2.0 - https://www.startech.com/uk/AV/Extenders/HDMI/HDMI-signal-booster-extender~HDBOOST4K

 

EDIT this one claims to work at up to 35m with HDMI 2.0 - https://www.lindy.co.uk/cables-adapters-c1/audio-video-c107/50m-hdmi-2-0-10-2g-repeater-p9014

 

There are also active cables available for longer lengths.


Edited by jonuk76, 04 December 2017 - 03:53 PM.

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#5 futuretrackstar

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Posted 04 December 2017 - 07:16 PM

Thank you jonuk76 and mightywiz for your suggestions. Looks like your suggestions and information agrees with the comments made by Vizio's advanced technical support team; specifically, my HDMI cable is TOO DAMN LONG. haha. I had no idea that a 4k signal would be degraded after 30ish feet, but that seems to be the case. This also explains why I once saw a 4k signal appear for just a fraction of a second on my TV using this long cable. I saw my computer's desktop flash on the screen when I had the resolution set to 4k, and then the TV went back to displaying the "no signal" error. I suppose the cable is just a little bit too long, and the signal is being degraded just a little too much. Explains why everything worked just fine with my 30 ft cable, but does not work with a 39 ft cable.

 

I will look into purchasing an active cable, or an HDMI signal booster/amplifier.

 

Thanks again for your help!



#6 jonuk76

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Posted 05 December 2017 - 08:18 AM

No worries

 

Yep there is no problem at all with short cable runs.  It's a little bugbear of mine that companies sell ludicrously overpriced HDMI cable for short runs and claim (with assistance from a compliant AV press) that it somehow results in better picture/audio quality.  Rubbish.  Over longer distances cable quality is a factor though, and what worked for 1080p/60hz will not necessarily still work at 4K/60hz with 10 bit colour.

 

When you buy, I'd suggest dealing with a supplier with a no hassle return policy, just in case of any issues.


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#7 mightywiz

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Posted 05 December 2017 - 01:17 PM

here's the quickie technical side:

 

longer cable runs increase resistance values in the cable, also wires running in parallel create capacitance (your hdmi cable has several wires that run parallel).  both together change how components work at the current & voltage level, which can effect communications across the wire.

 

that's why you need to booster/repeater to compensate for the extended lengths.



#8 mjd420nova

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Posted 05 December 2017 - 01:57 PM

This is often confusing to me as I use two 25 foot HDMI cables with a female to female connector in the middle to run the video from my desk top to the HDTV in the living room.  Have never had any trouble with loss of signal or reduction in resolution due to the cable being too long.  I bought the cheapest cables at Fry's for that length and expected to have to put a repeater in the middle but the F2F works fine.  There is an issue with the TV blanking for a second when on tuner input when I turn on the desktop.  Some handshaking going on that resets the TV when the HDMI sees another source, but not a real problem.  I have encountered this in other set ups too so I wonder about the TV having ignored the HDMI inputs once it's powered up and the activation of the port causes the TV to reassign ports.  Doesn't happen in all cases.






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