I've got a strange question with my dual Dell U2711 monitor setup which is hooked up to a Radeon HD 6950 derivative: one is connected to the dual-link display port at 2560x1440, and the other is connected to DisplayPort at 2560x1440 because I can't get 2560x1440 on DVI with two displays.
Dell acknowledged to me about a year ago that the U2711 doesn't work well with DP configurations. This was in Twitter over a direct message with them basically saying "there are issues with DisplayPorts", so I didn't get enough clarity nor do I know if I can address this as well as I'd like or even at all.
The issue seems to have some OS specificity. For example, I was on Windows 7 until last month, and normally, the monitor would go to sleep after 1 minute and then wouldn't power on every so often (but rarely). I'd end up rebooting the PC to get the computer to "kick" the monitor awake again.
In February, I upgraded to Windows 8. Now, the problem manifests itself completely differently and far more often: the DP connected monitor doesn't always power off. It dims, sometimes displays colorful squiggly lines as if the monitor is broken. Sometimes it looks like a black screensaver is on (the monitor screen is powered on, rather than off). Sometimes only about 50% of the screen is dimmed and the rest is visible "behind the dim." I can provide pictures if need be. I'd say the power-off in monitor-sleep mode is hit or miss; 60% of the time, it exhibits the behavior I described - 40% of the time, it powers off as I desire.
Does anyone know a way around this, save for buying a new video card or upgrading my U2711? I like having two identical monitors with identical resolutions, so I'm not really keen on that idea...
I should note that I replaced my U2711 about 4 times, went to a U2713 for awhile, and someone had a U3011 who also reported the same issue. I use an Accell cable to no avail. It's a DP issue with Dell high resolution displays. Why? How do I fix it?
* List all the ports on the Radeon HD 6950. Are the Radeon HD 6950 DP (Display Port) full size or mini?
* Break out exactly how the U2711s are connected to the video card using what ports and what cabling. For example =
Computer Radeon HD 6950 DP --> Dell DP to DP cable --> #1 U2711 Full size DP
* For power save issues troubleshooting, disconnect the U2711 USB upstream cable from the computer USB ports. Disconnect all USB devices from the U2711.
* The U2711 DVI ports are DVI-D Dual Link. When testing DVI from the Radeon HD 6950 to the U2711, you must be using the Dell provided DVI-D Dual Link cable.
Here's one better. This is the Radeon HD 6950 that I'm using:
2 x Mini DisplayPort
2 x DVI (1 Single Link, 1 Dual Link)
Computer Radeon HD 6950 DVI - Dell DVI cable - U2711 Full size DVI (this is not where my complaint lies, so I am not sure why having a Dell DVI cable makes a difference, frankly)
Computer Radeon HD 6950 DP - Accell DP cable (I also tried the Dell DP cable) - U2711 Full size DP with issues
Dell told me earlier that they have issues with the DP connections, Chris, and I even got 3-4 new replacements that exhibited the same exact behavior. From what you're telling me, I'm no closer to finding a solution.
Let me show you what my DP looks like. This is SLEEP MODE, to be clear, or otherwise known as Power Save mode.
Not exactly, Chris. The issue persisted on Windows 7 (the computer wouldn't recover from Sleep Mode), but I only had this particular issue in Windows 8. If you reread the original post, the issue got particularly bad in Windows 8 only, and those pictures show you what behavior I encounter now. I only had access to one monitor on Windows 8, but I had access to four in Windows 7. Are you saying DP isn't a problem with U2711s? Based on the Anandtech thread that I originally posted this on (see http://forums.anandtech.com/showthread.php?t=2373847), a guy also reports similar issues with the U3011.
Are you saying DP isn't a problem with U2711s?
* No. But if the issues do not occur on another computer, the monitors are fine. This is a simple way to check if the computer or operating system DP link coming out of sleep mode is at fault.
* The U2711 came out in 2009. I have not seen any firmware updates for it in years. Are these still under warranty?
"I have not seen any firmware updates for it in years." Which is probably the problem. 😞
And yes, both monitors are still under warranty (I believe I have 2.5 more years). I got the U2713 once though and was totally unhappy. Maybe the "new" U2713H would be fine, but I don't know. I would want to replace both monitors as I want to have a consistent experience... and DP is bad with the U2711 (and U3011) in general.
My U2711 displayport connection started having this problem and after trying different cables/connections and just about giving up... I tried unplugging the USB cable and restarting. That fixed it!
Note: DVI cable would still work even with USB still plugged in... I have not tried plugging the USB back in and don't plan to! I didn't need it anyway.
I didn't restart, I had to unplug the USB cable to get the displayport to start working again.
I had 2 monitors, both connected via displayport to a Quadra 2000 in a Dell T1650. The displayports had been somewhat flaky to setup in the past but I always got them going eventually... Then I removed the second monitor, a Dell 24 inch, and when I rebooted the system, the 27 inch monitor said there was no signal and went into sleep mode. I plugged the 24 inch back in and it came up, but the 27 inch remained in sleep mode. So I switched out cables and tried both display ports on the Quadro 2000, but the 27-inch would not activate. I started to think the monitor had failed, so I plugged in a DVI cable to the 27-Inch and it started working fine. So I plugged the displayport back in and chose that as the input (on the monitor input menu) and it still would not work.
Then I saw this post about removing the upstream USB cable if it was installed... Sure enough once I unplugged the USB connection, the displayport connection came back to life.
So that is how it was solved for me, although I suppose it could have been just a coincidence...