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JogerJ

[RANT] Buying experience of DisplayPort cable just plain sucks

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Posted · Original PosterOP

Recently I got myself a cheap used monitor for a secondary monitor that supports DisplayPort for 50€, which unfortunately didn't come with a display cable. No matter. I already used the HDMI ports on my GPU, so I figured I could use the DP port that's free on the GPU. So I was looking for a DP cable to do the job. Since it's a 75Hz 1080p monitor (basically nothing special), I wanted to cheap out as much as I can with the cable.

 

And then I read about the 20 pin DP_PWR debacle and how allegedly it can short-circuit and be harmful for my GPU. The only guarantee people have been saying is to get a VESA certified DP cable. 

 

Yet, here are several problems that I found with trying to buy a VESA certified DisplayPort cable:

  1. Most cable manufacturers seem to won't bother having their cables VESA certified (VESA ceritication requires membership which cost a fee, yet so does HDMI though). Those who do are certifying their high-end cables that supports DP 1.4, which I know I won't need, and then they sell their cables at about double the price of no-brand cables that "claims" to do the same, or even more compared to DP 1.2 cables. VESA's website lists around a thousand registered products while HDMI lists nearly 2000 "adopters" (which may have more than one product each).
  2. Sellers would sometimes advertise their product to be VESA certified and supposedly you can check its validity on VESA's website, but the problem is the seller doesn't always use the brand/name of the manufacturer's. Take for example the AmazonBasics DisplayPort, which lists itself as VESA certified, yet you can't find Amazon on the list in VESA's database. In fact, a lot of the listings are made by OEM manufacturers, which are often not mentioned at all when the actual end product reaches the customer. After reading reviews, it turns out somebody commented that the 20 pin on the AmazonBasics cable is active, even though it's supposedly VESA certified.
  3. The usage of the DP logo supposedly indicates the product to be VESA certified, which unfortunately is easy to fake and there doesn't seem to be any countermeasures taken against it.
  4. If the cable you're using isn't VESA certified and turns out to be defective that it damages your GPU/MB/Monitor/device, your warranty may become void because it's technically "misuse/improper use/operation outside of specifications". The device manufacturer would blame the cable manufacturer and vice versa. At least with uncertified HDMI cables, you're not at risk of short-circuit that happens because of intentional design of the cable. There's uncertainty whether a DP cable is "safe" to buy and as a consumer I wouldn't bother getting a multi-meter to check whether my 20 pin is connected or not.

If this were an HDMI cable, at least I don't have to worry about getting a certified cable in the first place, there's no risk of damage by default, at most you probably don't get the correct display resolution/colors or similar problems (short-circuit occurrences with HDMI I could find were caused by the device connected to being faulty or bad wiring/grounding on the connected devices [1][2][3], not the display cable itself).

 

In the end I settled for a DP8K certified cable, I couldn't find anything cheaper that's verified VESA certified. It's overkill, completely unnecessary, yet I don't want to fry my electronics either. 

EDIT: More info on 20 pin problem, which just shows how the problem has persisted for years and how it's still relevant today:

https://www.tenforums.com/graphic-cards/137524-experienced-pin-20-display-port-problem.html

https://forums.tomshardware.com/threads/is-19-vs-20-pins-displayport-still-a-thing.3017713/

https://www.reddit.com/r/nvidia/comments/a1nmej/psa_please_do_not_use_dp_cables_provided_with/

https://en.wikipedia.org/wiki/DisplayPort#DP_PWR_Pin

 

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Almost anything that doesn't feel cheap is better than whatever comes in the box of most monitors.  You won't fry your board, cos there's no power coming from your monitor, but it can cause boot issues that can be fixed with swapping out the cable or unplugging that cable prior to booting.  It also isn't consistent.  I get this issue once every few months at most.


QUOTE ME IN A REPLY SO I CAN SEE THE NOTIFICATION!

When there is no danger of failure there is no pleasure in success.

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43 minutes ago, JogerJ said:

Recently I got myself a cheap used monitor for a secondary monitor that supports DisplayPort for 50€, which unfortunately didn't come with a display cable. No matter. I already used the HDMI ports on my GPU, so I figured I could use the DP port that's free on the GPU. So I was looking for a DP cable to do the job. Since it's a 75Hz 1080p monitor (basically nothing special), I wanted to cheap out as much as I can with the cable.

 

And then I read about the 20 pin DP_PWR debacle and how allegedly it can short-circuit and be harmful for my GPU. The only guarantee people have been saying is to get a VESA certified DP cable. 

 

 

 

I wouldn't worry too much about it. To give you an example of "faking a DP cable" If you take two DP to DVI cables, both which should be powered by the DP_PWR by both devices, the cable will not work. The reason? The one on the monitor will not be powered. However two HDMI to DVI converters will, because they only pass the signal.

 

Now I can't guarantee that a cheap cable won't do this, but it's been present experience that the monitors do not connect the DP_PWR pin, only the device (eg the GPU) does. So unless you were getting uncertified cables from 2013 (yes 7 years ago), it's likely any cable you purchased should be at least DP 1.2. Including those included with monitors.

 

If you're paranoid, just buy a certified cable from brands actually known to be certified, and avoid the 99 cent counterfeit cables you find all over ebay and amazon.

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14 hours ago, Kisai said:

I wouldn't worry too much about it. To give you an example of "faking a DP cable" If you take two DP to DVI cables, both which should be powered by the DP_PWR by both devices, the cable will not work. The reason? The one on the monitor will not be powered. However two HDMI to DVI converters will, because they only pass the signal.

 

Now I can't guarantee that a cheap cable won't do this, but it's been present experience that the monitors do not connect the DP_PWR pin, only the device (eg the GPU) does. So unless you were getting uncertified cables from 2013 (yes 7 years ago), it's likely any cable you purchased should be at least DP 1.2. Including those included with monitors.

 

If you're paranoid, just buy a certified cable from brands actually known to be certified, and avoid the 99 cent counterfeit cables you find all over ebay and amazon.

DP_PWR is provided from both sides. That's the reason they should never be connected with a straight wire, because you're connecting two voltage sources together.

 

The reason DP to DVI adapters don't work in both directions is because DP outputs the DVI signal at 3.3 V, and the adapter has a level shifter circuit which converts the 3.3 V to 5 V, and this only works in one direction, so the adapters are not bidirectional. Most DP inputs also don't accept DVI signals as input, it's just the output ports that can send both types.

 

@JojerJ I have to agree it's unfortunate the VESA database is practically useless. They should be giving out some kind of certification ID number to be listed on product pages, which can be searched in the database to pull up the product it was issued to, so you can easily confirm products. Instead, it's just "here's the list of every product ever certified". And they need to standardize their notation and format (some cables are listed as DP8K, some are listed as HBR3, etc.).

 

But then again, that's why I pinned a Guide thread with direct links to certified cables, since people often have trouble finding them.

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