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Akasata111
Phosphor

Latitude E7470 produces flashing/blinking image on 4k monitor connected to docking station

I have a brand new Latitude E7470 that I'm trying to connect to a 4k monitor thorough an E-port plus II docking station. Unfortunately the image keeps blanking out on the monitor, at a variable rate between once a second and once every few seconds. I've tried both a displayport cable and a DVI-to-HDMI cable for the connection, and the result was the same. Changing the resolution did not help either.

I am running the latest BIOS and latest Intel graphics driver from the dell support page (both about a week old). (By the way, the BIOS update messes up the OS installation - buyer beware.)

I've tried many other combinations to trouble-shoot the issue:

1. Different laptops (E64xx), same E-port, same monitor -> works fine

2. Same E7470, different E-port (old USB 2.0), same monitor -> monitor blinks

3. Same E7470, same E-port, different brand 4k monitor, different DP cable -> monitor blinks

4. Same E7470, same E-port, monitor switched to DP 1.1 -> monitor stays black

5. Direct connection between the E7470 and the monitor via HDMI -> works (but only at 30 Hz due to HDMI limitation)

So the conclusion is that the combination of E7470 + E-port + 4k monitor doesn't work, regardless of the exact monitor or exact E-port. That leaves the E7470 as the only logical culprit.

Is this problem a design limitation of the E7470, a known driver issue or a faulty notebook?

Thanks in advance!

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8 Replies
xxbigbacon
Copper

RE: Latitude E7470 produces flashing/blinking image on 4k monitor connected to docking station

I am also having a similar problem with my 7470. Newest bios and drivers are installed. Happens on both the laptop's screen and using an external monitor through a docking station.

Seems to start after the monitor has been turned off due to PC activity. Can fix it with a restart OR by changing the resolution and changing it back. Both highly annoying options. Switching from external to laptop screen does not fix it, it will continue.

my external screen is using a DVI connection from the dock to the monitor which is also DVI so I am not using some kind of adapter. Removing the connection from my KVM does not resolve the issue either.

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sfornaro
Phosphor

RE: Latitude E7470 produces flashing/blinking image on 4k monitor connected to docking station

Hi I have the same issue you described.

I have a Latitude 7470 and the Dell E-Port docking station (old generation : usb 2.0). I have two 23" LG screens (LG IPS235V-BN) connected to the Docking using DVI cables. Everything works fine untill the Latitude goes to sleep. When it wakes up, the right monitor starts to blink (image goes dark every now and then - the frequency varies from 5 to 10 seconds to 30 seconds, the image disappears for just one or 2 seconds and then it comes back). Of course I already tried several combinations, changing the cables and so on, but the issue is really related to the one of the DVI ports on the Docking - or I would rather say, to what is wired to that port inside the Latitude, as I don't have the issue with my other (older) latitude laptops.

I was using the same screens and same docking station with my 2 previous Dell Latitude laptops (E7440 and E4200) and it was working without any problem.

I'm running Windows 7 Pro 64 bits (6.1.7601), the CPU is an Intel Core i7 - 6600U, with 32 GB of RAM (2 x 16 GB DDR4 G.SKILL F4-2133C15S-16GRS - yes I know it's not an officially supported config, but it works) , I have a 500GB SSD (Crucial MX200 M.2 2280 - well this one is also not part of the standard config) , and my HD Intel configuration panel states that the drivers version for the Intel HD Graphics 520 are : 20.19.15.4326, BIOS version : 1033.10

It would be interesting to share the details of your config guys,

Did you find a solution to the issue in the mean time?

Thanks

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RE: Latitude E7470 produces flashing/blinking image on 4k monitor connected to docking station

Same issue here. E7270, E-Port dock, 1 x Samsung UHD (4k) and 1 x Dell S2409.

Have tried all the troublshooting above,(e.g. changing cables, updated bios, video drivers etc), also tried this apparent fix: http://www.dell.com/support/home/us/en/19/Drivers/DriversDetails?driverId=WNV4C&fileId=3534260691&os... linked to in another thread I found. Same symptoms persist. Interestingly its only my 4K monitor that's having the issue, but it's driving me MAD! I've even tried changing resolution just in case, no difference.


Help!

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Akasata111
Phosphor

RE: Latitude E7470 produces flashing/blinking image on 4k monitor connected to docking station

After 2 months of talking to various support organizations within Dell on an almost daily basis, they declared that 4k monitors are not supported by this configuration and closed the issue as far as they are concerned.

In the meantime all the other symptoms (flashing monitors in FHD resolution, daily random reboots, no signal on either internal or external monitor until reboot) have returned.

So if you are within the return window, I would very strongly recommend returning the unit, and purchasing something from a reputable vendor.

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sfornaro
Phosphor

RE: Latitude E7470 produces flashing/blinking image on 4k monitor connected to docking station

Hi Guys,

This might fix your problem :

www.dell.com/.../DriversDetails

This firmware is supposed to fix an "MST hub" issue, please read installation instructions carefully as the computer must be installed on the docking station and connected to the external monitor at the time the firmware is installed.

I'll try it and let you know if it worked.

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sfornaro
Phosphor

RE: Latitude E7470 produces flashing/blinking image on 4k monitor connected to docking station

I tested it and it worked for me. The flickering is now gone after the laptop resumes from standby and is docked, and external monitors are connected to the docking station.

Hope this fix will solve your issues as well

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RE: Latitude E7470 produces flashing/blinking image on 4k monitor connected to docking station

Thanks very much.

Unfortunately, if you read my post again you will see that  I already said I'd tried that (I posted the same link saying I'd tried it!), it made no difference at all for me.

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Akasata111
Phosphor

RE: Latitude E7470 produces flashing/blinking image on 4k monitor connected to docking station

Just a quick update 2 months later: flashing and crashing is getting more and more frequent, despite some new driver updates. It is becoming nearly impossible to work with the laptop. At this point I would very strongly advise against getting this machine (or anything from Dell, as a matter of fact). If Dell cared about their customers, they would recall this model. But who am I kidding?

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