Hello Victor_se, I am sorry to hear that have had problems with your NUC.
According to the graphics team the latest graphics driver included a fix related to flickering.
I would recommend installing the latest graphics driver version 3621. You will be able to find it at the following URL
I have a flickering problem as well, for me it is very noticeable and annoying when watching TV content via Windows Media Center (Windows 7 Pro 64-bit) and the flickering generally happens when there is a greater amount of lighter colors on the screen.
Problem happens with the Intel HD 5000 video card on the NUC D54250WYKH.
With latest bios and drivers, so don't give me the standard "update drivers" line, please. :-)
The problem DOES NOT happen with the Intel HD 3000 in the Lenovo Q190!!!
I attached the Lenovo Q190 to the same TV with the same HDMI cable, same Win7 Media Center configuration and TV content DOES NOT flicker like the NUC.
I had the same flicker problem with my D54250WYKH1. I'm using Windows 7 Ultimate 64bit, Windows Media Center with a SiliconDust HDHomeRun Prime 3 tuner. The local channels worked fine but the pay channels like History, HBO, etc. would often have a flicker or strobing effect.
One thing that helps a lot is to disable Contrast Enhancement. The Intel control panel for the HD 5000 (11-2014) is hiding this setting. Right click on your desktop and select graphics properties. This should bring up the Intel hd graphics control panel. Click the video icon, then click the down arrow in the upper left corner of this window. NOT the down arrow next to current settings, but the down arrow right next to the word Video. Select Image Enhancement, then select Advanced. About half way down the screen is the Contrast Enhancement that needs to be disabled. Don't forget to select apply and yes.
Other unrelated tips for using this NUC box as a HTPC: Use a wired network if at all possible. Try a short usb2 extension cable on devices that don't work properly on the NUC's usb3 ports. Google Shark007 and install the free codecs to play many more video files within Windows Media Center. HP media center remote, EventGhost, Logitech K400.