Hacker's ramblings

I spend lot of time doing stuff with a computer or computers to be exact. As a heavy-duty user, I love to have good displays to do the computing with. As every thing in consumer electronics, also monitor technology has improved a lot.

One of these days, I wanted a new monitor with really good spec.
Delivery guy brought me one, I installed it into my VESA monitor arm and then everything turned sour.

My expensive monitor "kinda" worked. Picture was there, it was crisp, backlight was really good, HDR-colors were really vivid until the monitor chose to flicker a bit and black out. This unfortunate blackout was a totally random event. It could occur three times per minute, or alternatively there could easily be 20 minutes without problems. Such random problems are very difficult to troubleshoot. In any easy case, reproducability is the key. No such joy here.

When in doubt - Google the problem!

Obviously, I went online with a description of the symptoms. Quite soon, this is what I found from Reddit: I'm having screen flickering/blackout via Displayport on my new 1440p 144 hz monitor. The suggestions pointed towards testing different cables and discussion about DisplayPort versions. Good ideas!

GPU

From GPU spec:

Confirmed GPU DisplayPort to be at version 1.4.

Previous Monitor

Spec says:

Confirmed old monitor DisplayPort to be at version 1.2. Hm. Everything worked at 4K resolution, no 144Hz though.

New Monitor

Spec:

Confirmed monitor DisplayPort to be at version 1.4. Equal to GPU.

Maybe the problem IS with the cable as suggested in Reddit!

Theory: DisplayPort Cable

Doing research on DisplayPort: DisplayPort 1.4 vs. 1.2: What's the Difference?

DisplayPort 1.2, originally released in 2010, offers more bandwidth than all but the latest HDMI standards.
DisplayPort 1.4 is a much more capable standard, with limited competition from even the latest and greatest

DisplayPort 1.4 supports resolutions of up to 8K at 60Hz or 4K at 240Hz
DisplayPort 1.2 supports resolutions of up to 4K at 60Hz

Doing research on cabling: How to Tell the Difference Between Display Port 1.2 and 1.4 Cables

Just to be clear, DisplayPort cables are not classified by version, they are classified by the amount of bandwidth they can handle.

Good thing there was a DisplayPort cable with the monitor. Changed it into use and oh yes! Flickering was gone.

Wikipedia says in DisplayPort -article:

There are seven (7) different specs for a cable. Well, that's a surprise.

Practice: DisplayPort Cable

Let's look at those cables bit closer. This is the non-functioning one:

There are zero clues on cable spec. Nothing! It has WEEE label and CE marking, that's all. Given reality, I'm guessing it is HBR / HBR2 -spec.

This is the good cable:

Still no idea of cable details. DisplayPort-logo with 8K suggests spec to be at least HBR3.

Reality Check

There is really no way of telling how fast a DisplayPort-cable is by hooking it into a computer or eyeballing it.

Beware: Most DisplayPort cables aren't sold with correct information
Aow come on! This is horrible.

Good thing is my money wasn't wasted on a faulty unit.