slabhatnik
Limp Gawd
- Joined
- Sep 19, 2013
- Messages
- 133
@FinnishNerdmare : Hope this helps.
Here is an old post on this problem, I've updated the links...
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Old 01-23-2011, 02:29 PM
musicfan n00bie, 2.9 Years
Problem Solved
Hi, I'm a first time poster. I discovered this thread while I was researching a different DisplayPort problem, having to do with certain Dell monitors such as the 30" U3011 not being able to wake up after the DisplayPort input goes into sleep mode. I still haven't come up with a solution to that problem.
Anyway, I do know why you are having so much trouble with the MonoPrice DisplayPort cables, as well as those from some other vendors. The problem is that these cables don't follow the DisplayPort guidelines, which require that pin 20 be left unconnected. This is essential, because pin 20 supplies power to external devices, and is provided by any device with power, including computers and monitors. If you connect two powered devices via pin 20, all sorts of bad things can happen as both try to control the voltage on the line. If your monitor or computer is off and the other device isn't, the powered device will try to provide power to the unpowered one via your DisplayPort cable! If you check the official cable that comes with your monitor, in the cases where one is provided, pin 20 will not be connected. Pin 20 is easy to identify, as it's the one that's next to the part of the connector with a 45 degree angle.
I ordered a mini DisplayPort to DisplayPort cable from MonoPrice and it did have continuity on pin 20, which caused problems for me. I informed them about the issue, and provided references (see below), but so far they have not pulled the cables from their site, and even tried to replace my cable with another of the incorrectly designed cables. Perhaps if more of us express our opinions to them, they will finally issue a recall. I've wasted lots of time with this issue that I really didn't have to waste, so it irks me that they are dragging their heels about doing something to correct this situation. Up until now, I've been a big fan of their products.
Here are the references that I promised. The first is the official DisplayPort web site's FAQ:
http://www.displayport.org/faq/
Q: Why isnt there a wire on pin 20 (POWER) on the standard external DisplayPort cables?
A: The reason power isn't included in standard cables is because both source and sink devices are designed to provide power. Captive, attached cables often include the power wire. If it is desired, for example, that a particular source device utilize the power available from the mating sink device, then that Source device could include an attached or dedicated cable that carries the DisplayPort power signal. Same could be applied to a sink device.
The second is a warning notice from NEC:
http://www.necdisplay.com/documents/Miscellaneous/DisplayPort_Notice.pdf
I sincerely hope that this message saves somebody from going through the same trouble that I have.
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Whoa.... this might be the cause of a gpu not waking from sleep I've had (and given up on) from 2 years ago with on a asus p5gc mx hackintosh I had done... will test it tomorrow- thanks for the pin 20 info..........