Multiple monitor issues: no 60hz via HDMI, black screen via DisplayPort


I am using Gentoo Linux, an ASUS nVidia GTX960. My monitor is a Samsung U28E590.
Driver version is 378.13, kernel version is 4.4.45. version is 1.19.2. I use KDE 5 (not sure if this is relevant).

I have two distinct problems which really prevent me from enjoying my current configuration:

1/ When I connect the monitor via HDMI, it gives me a refresh rate of 30Hz instead of 60 (note that under Windows, it works well). Also, when the monitor goes to sleep, when it wakes up (I move mouse for instance), it takes a VERY long time to come back (it can take up to 30 seconds). Most funny is that it can get back to an application, then when I switch to Chrome (and only Chrome!!!) it goes black again and I have to wait 30 seconds to get it right on Chrome (if I alt-tab during this time to another app, it will go back). Sometimes, on Chrome, it never gets back and stay black.

2/ When I connect the monitor via DisplayPort, while the computer is booting, it works (probably the console uses a resolution of 1920x1080). But once X starts, the screen stays black. However, if I start X using the HDMI port, THEN remove the HDMI cable and plug in the DisplayPort, it works (and it works at 60Hz!). This is what I currently do. Once the screen goes to sleep, I have to always reach for the physical button on the monitor to turn it back on again (this does not happen with HDMI, although as written there are other problems with HDMI).

Note that in both cases (HDMI or DisplayPort), when I switch to console using ctrl-alt-F1, the screen stays black. I can switch back to X via ctrl-alt-F7 normally.

What should I do to improve this situation? I don’t have any xorg configuration file right now.

Link to (took while X was started via HDMI but switched to DP afterwards):


Update: I spent time today and now think for the HDMI problem, it may be a hardware issue. The Samsung monitor has 2 HDMI ports. When I use the second, everything seems to work better. I can get 60Hz refresh rate and there is no longer the “waking up” screen problem.

Note that I can’t still switch to console mode; and the DP problem remains.

Does the DP problem still occur with 381.22?


Does nomodeset kernel option help with console switching?

No, it did not. Here is my boot line:

[ 0.000000] Command line: BOOT_IMAGE=/boot/kernel-4.4.70 root=/dev/sda1 vga=0x031b nomodeset ro

I added the nomodeset, but console switching is still KO.

Any ideas?