This article provides the information on "UltraSharp U2515H/U2715H loses video during boot-up or power save recovery or monitor screen flashing intermittently while on".
A Dell customer with multiple Dell and non-Dell Windows based systems with Dell U2515H/U2715H displays connected via DisplayPort directly to the dock DP ports and not daisy chained, noted on systems configured for dual monitors one or both displays would intermittently flash blank or show a black screen. This also happens during boot-up and during Power Save recovery.
Powering off the display and powering it back on would restore the display until the issue re-occurred.
Updating the BIOS and Graphic adapter drivers had no effect on the issue, nor did changing DisplayPort/mini-DisplayPort cables.
This workaround was effective on Latitude E7450 & E5250 systems by changing the default DisplayPort mode in the U2515H/U2715H On-Screen Display (OSD) and enabling DisplayPort 1.2. This solution may also work on other system models. (See Figure 1.)
Figure 1. Enabling DisplayPort 1.2 in the On-Screen Display (OSD).
If you need to reset the display to DisplayPort 1.1a mode when the display is not showing an image, use the steps indicated in Figure 2 below:
Figure 2. How to change the input select option in the On-Screen Display (OSD) menu.
On systems equipped with a MST Hub (See if the firmware download is listed on the Dell Support Website for your system), Updating the MST firmware is also recommended. You can download the firmware update from the Dell Support Website.
Article ID: SLN298210
Last Date Modified: 08/14/2017 02:12 PM