weird dots on display

[Avi Assayag]

I have this weird problem:
I'm running a beast pc with 2 monitors. first monitor is a 42" tv connected with hdmi (tv) and dvi (pc), via a short cable. The second monitor is a 50" tv connected with hdmi over a 30 ft long cable to the living room.

first monitor works perfect with the short cable. the second one has very strange weird dots all over the display.

I switches cables, cards and pc's and this is the situation: the dots appear only in the long cable 's tv and only when connected to DESKTOP GPUs. I've tried amd 7990, gtx 980ti, gtx1060. all with the same result. but when I connected laptops (3 of them, with and without discreet GPUs) all was well in both monitors. the problem disappeared. now I know it has a specific issue with desktop gpus. any suggestions??

 

[RememberThe5th]

No, its just limitation for lenght.
http://www.tomshardware.co.uk/forum/310741-33-maximum-lenght-hdmi-cable-computer
There is saying that you can buy category 2 HDMI cable which can run up to 50 ft (not sure??)

 

[Avi Assayag]

I see, but firstly, the cable is hdmi 2.0, and secondly, if it was a length issue, it would not be resolved with a laptop being connected. it ia isolated solely to desktop GPUs

 

[RememberThe5th]

Well if you use cheap cable, then it could by "technical standard" but have you pushed HDMI till it clicked? It happened to me once i was wondering why isn't working.

 

[Avi Assayag]

yes, it did click. again, I'll clarify and emphasize that it only happens in desktop. not with laptops though. it's something to do with the desktop gpu

 

[RememberThe5th]

Not sure... Wait for other answers cause i have no idea. I've never tested that theory or proof.

 

[Avi Assayag]

I have narrowed the issue:

I used 2 other TV's, and the picture was crystal clear.

only on the big 50" the dots occurred. BUT - only with the ultra long cable. with a regular cable it was all good.

any suggestions?