Have bought myself a Dell Ultrasharp 2560x1440p monitor, running it over HDMI from my Lenovo U430T. This laptop has Intel HD4400 + GT730M, i5 4210U.
I'm getting horizontal occasional single pixel height red, green and blue flashes, and occasionally youtube HTML5 video is a bit choppy despite being loaded.
I'm also getting occasional black screen... flashes? (The screen just goes black for a split second).
Any help would be great guys :)
The black screen or flashing could be due to the laptop switching between the HD4400 and GT730M card. Although, I am not entirely sure.
I am running with a laptop at work with a similar combo of graphics cards. Setting the power profile to performance or balanced helped a lot here.
My screen is connected via DVI to a docking station though, haven't tried HDMI on anything else than a Full HD TV which worked fine.
Maybe your HDMI cable is dodgy? Do you have some other source you can test with or try a lower resolution to see if the problem persists?