Displayport entering power save mode problem

[FatalFlaw]

I just got my new Dell U2713HM and it's connected via DP to my 5870. I also have two other monitors connected via DVI. Windows is set to put the monitors in power save mode after 15 minutes without use. This part works, but then the U2713HM doesn't wake up. The other two monitors do, but the dell just sits there in power save mode. Reseating the DP cable sometimes causes it to wake up, but not always, in which case I have to reset the computer. I've not encountered this before and was hoping someone had some suggestions.

 

[CakeMonster]

Nope. Not solvable it appears, other than not setting the monitors to sleep. I don't let my monitors sleep. I turn off my DVI monitor and let the black screensaver run on the DP one. That means that my U2711 has run its backlight for almost 3 years now without being off.

You can let it sleep but you'll have to deal with resizing and moving all the stuff that was on that monitor after you waked it up or enable it again. I choose not to do that since it would drive me crazy.

There's several threads on the Dell forum about the U2711 but it the problem appears to be DP and not that model. The Dell representatives repeatedly refuse to acknowledge it, and suggest checking cables etc. People have even tried modifying DP cables to disable a supposed sleep pin, but nothing seems to solve it.

I've given up on this long ago, and I just accept that one of my monitors will have a shorter lifespan. Luckily I only have one additional monitor in need of DP (1440p/1600p needs it since no current cards have more than one DL-DVI).

 

[FatalFlaw]

Nope. Not solvable it appears, other than not setting the monitors to sleep. I don't let my monitors sleep. I turn off my DVI monitor and let the black screensaver run on the DP one. That means that my U2711 has run its backlight for almost 3 years now without being off.

You can let it sleep but you'll have to deal with resizing and moving all the stuff that was on that monitor after you waked it up or enable it again. I choose not to do that since it would drive me crazy.

There's several threads on the Dell forum about the U2711 but it the problem appears to be DP and not that model. The Dell representatives repeatedly refuse to acknowledge it, and suggest checking cables etc. People have even tried modifying DP cables to disable a supposed sleep pin, but nothing seems to solve it.

I've given up on this long ago, and I just accept that one of my monitors will have a shorter lifespan. Luckily I only have one additional monitor in need of DP (1440p/1600p needs it since no current cards have more than one DL-DVI).

That seems like a major problem not to have a fix for. Does anyone know exactly which piece of hardware causes it? Is it the monitor, cable, or video card? I just setup two U2713HMs using displayport connected to an NVS300 card at work and it doesn't have any sleep issues. This would lead me to believe it's either a cable or card issue. I wasn't planning on buying a new video card until the next line comes out, but I suppose I could borrow one from work and see if that resolves it.

 

[imagoon]

My U2711 sleeps and awakes using display port fine. ATI 7870 with recent drivers running it.

 

[FatalFlaw]

My U2711 sleeps and awakes using display port fine. ATI 7870 with recent drivers running it.

Yeah, I'm going to have to try swapping cables and cards. Looking around, this seems to be a common complaint, but there's wildly conflicting reports of what causes it and how to fix it. Some of the fixes are completely nonsensical and I was hoping someone here might have better reasoning than I've seen elsewhere.

 

[CakeMonster]

My U2711 sleeps and awakes using display port fine. ATI 7870 with recent drivers running it.

Are you using a mDP-DP cable?

Another thread here on AT with people experiencing the same or similar problem:

http://forums.anandtech.com/showthread.php?p=34608946

 

[FatalFlaw]

Are you using a mDP-DP cable?

Another thread here on AT with people experiencing the same or similar problem:

http://forums.anandtech.com/showthread.php?p=34608946

It's full sized displayport. The output on the card is full sized DP and the input of the 2713HM is full sized displayport. I'll check out the link anyway in case it's still relevant though.

Edit: Ah pin 20. I don't know if that's the issue or not. I'm going to test another cable tonight when I get off work. If that doesn't work, I'll try removing pin 20 from the cable and see if that makes a difference. I'm going to be pissed if it's caused by non-compliant cables.

 

[imagoon]

Are you using a mDP-DP cable?

Another thread here on AT with people experiencing the same or similar problem:

http://forums.anandtech.com/showthread.php?p=34608946

mDP -> DP

 

[jackstar7]

Just one thing you can try is going to the Screen Resolution screen and hitting Detect to see if it brings it back in line.

 

[CakeMonster]

Edit: Ah pin 20. I don't know if that's the issue or not. I'm going to test another cable tonight when I get off work. If that doesn't work, I'll try removing pin 20 from the cable and see if that makes a difference. I'm going to be pissed if it's caused by non-compliant cables.

Well, the pin 20 thing did not work out for a lot of people, even frustrated people who bought expensive new DP cables in the thread on the Dell forums. So it could be a red herring. Experiment with what you have before spending money on it.

 

[FatalFlaw]

Just one thing you can try is going to the Screen Resolution screen and hitting Detect to see if it brings it back in line.

Good thought but I've tried that and it doesn't bring it back. Interestingly, the screen is detected and the video card treats it as being there in that even though you can't see any image on the U2713HM (middle screen), you can tell it's there by the way the other two monitors behave. You can move windows onto the sleeping display and, if you get lucky with where your click, you can grab windows on the sleeping display and drag them to one of the awake ones.

 

[lurk3r]

FWIW in the last 6 months my 5850 has started doing exact same thing, 2 monitors on DVI, nothing on display port. I've tried multiple different drivers that were supposed to fix the issue, in the end I gave up and disabled the screen saver and power the system off every night now. Watching for a deal on an nVidia card to replace this with and RMA it to XFX (again).

 

[FatalFlaw]

FWIW in the last 6 months my 5850 has started doing exact same thing, 2 monitors on DVI, nothing on display port. I've tried multiple different drivers that were supposed to fix the issue, in the end I gave up and disabled the screen saver and power the system off every night now. Watching for a deal on an nVidia card to replace this with and RMA it to XFX (again).

That's interesting. I don't know if it's the same thing or not. Mine only affects DP and I've read a lot of other complaints also only about DP. I've not previously used the DP port on my video card because I've always used the to DVI ports. It's only now that I have three monitors that I've started using the DP port. Have you tried swapping out cables?

 

[B-Riz]

FWIW I also have DP problems with a 7950 and HP LA2405x; comp wakes monitor does not, and the monitor OSD does not see DP as active until I unplug the cable from the vid card and plug it back in.

I think there is either an implementation issue of the port or driver issue somewhere.

 

[bradly1101]

I remember a BIOS setting: Reinitialize VGA BIOS on resume, or something like that. Maybe it will help.

 

[FatalFlaw]

I remember a BIOS setting: Reinitialize VGA BIOS on resume, or something like that. Maybe it will help.

I checked my bios and don't remember seeing that setting, but I'll check again after work.

 

[FatalFlaw]

Solved!

I tried a second cable with the same results. So I bent pin 20 out of the way on one end of the cable and now the monitor wakes up quickly and without fail. It's ridiculous that non-compliant cables are even an issue. I'll have to try and find one that is compliant because I don't like the idea of a hot wire that could cause a short if it bends back and touches something it shouldn't.

For the record, these were 6ft monoprice displayport cables.

Thanks for the info and suggestions everyone!

EDIT: False alarm. Not fixed. I guess I'll try another video card and see if that fixes the problem.

 

[B-Riz]

I am using a StarTech Model MDP2DPMM10 10 ft. Mini DisplayPort to DisplayPort Adapter Cable, so I guess I will order a new cable and see how it works.

 

[FatalFlaw]

I am using a StarTech Model MDP2DPMM10 10 ft. Mini DisplayPort to DisplayPort Adapter Cable, so I guess I will order a new cable and see how it works.

See my edit on the previous post. It seemed to have been fixed but now it's doing it again.

 

[lurk3r]

That's interesting. I don't know if it's the same thing or not. Mine only affects DP and I've read a lot of other complaints also only about DP. I've not previously used the DP port on my video card because I've always used the to DVI ports. It's only now that I have three monitors that I've started using the DP port. Have you tried swapping out cables?

Yes, cables, even monitors, it started only on my main 27" dell, the mouse would work on the 2nd 24" Acerbut I could not get any real functionality out of the PC, I assumed for a while it was the monitor, but when both started I tried swapping the older 23" Acer I had upgraded from, so 3 different monitors and 5 different cables have been used.

 

[B-Riz]

Am ordering one of these: Accell B143B-003J spec 1.2 compliant.

 

[FatalFlaw]

Am ordering one of these: Accell B143B-003J spec 1.2 compliant.

I've heard that's the only cable that's actually certified by VESA. I'm not convinced that's the problem I'm having though since disconnecting pin 20 didn't solve the problem for me. Hopefully it will fix yours.

I read a response from a dell rep on their forums (don't have the link anymore), and he said it was a handshake issue between the monitor and video card. He claimed that when the monitor goes into power save mode, the video card needs to actively initiate the handshake for whatever protocol DP uses.

I've done some more testing and determined that the DP connected monitor will wake up from power save mode if the computer resumes from sleep mode. If the monitor is in power save mode but the computer is awake (no sleep state), the monitor will not wake. It wouldn't surprise me if the video card initiated the handshake when the computer wakes from sleep, but not when the computer is already awake.

I'll test with a different (and newer) video card to see if it makes a difference.

 

[B-Riz]

I've heard that's the only cable that's actually certified by VESA. I'm not convinced that's the problem I'm having though since disconnecting pin 20 didn't solve the problem for me. Hopefully it will fix yours.

I read a response from a dell rep on their forums (don't have the link anymore), and he said it was a handshake issue between the monitor and video card. He claimed that when the monitor goes into power save mode, the video card needs to actively initiate the handshake for whatever protocol DP uses.

I've done some more testing and determined that the DP connected monitor will wake up from power save mode if the computer resumes from sleep mode. If the monitor is in power save mode but the computer is awake (no sleep state), the monitor will not wake. It wouldn't surprise me if the video card initiated the handshake when the computer wakes from sleep, but not when the computer is already awake.

I'll test with a different (and newer) video card to see if it makes a difference.

Given that info, could set power options to never turn off monitor so it only goes to sleep when the computer does.

 

[FatalFlaw]

Given that info, could set power options to never turn off monitor so it only goes to sleep when the computer does.

That is one option. It would be inconvenient to have to turn off the monitors every time I'm away from the computer but need it to keep running because it's doing something. Less so than having to reseat the DP cable every time but it's still not the fix I'm going for. Frankly it's an absolutely stupid problem to have and I'm more and more dead set on fixing it one way or another.

 

[TerryMathews]

Some monitors, like my HPs have an option to maintain the DP connection even in powersave mode. Fixed my issues. Check your monitors menu settings.