# monitor blanks ... input with kern.4.4 [SOLVED Hardware]

## albright

Hi all - this is a strange problem and may be unique to me  :Sad: 

I have an intel NUC5i7RYB

Since install kernel >4.4.0 I have the strange sympotm that

when I press the keyboard the screen goes blank for a second.

This doesn't *always* happen.

No error messages appear in syslog or .xsessionerrors.

My system is weird because it has a device that splits the mini dp output

to two displayports for dual monitor support (which works fine). 

NOte that it is the screen on which the active app (the one I am using

the keyboard to enter data) that goes blank.

As I said this does not happen with kernels < 4.4.0

I should say that I'm mostly running kde 5 but the same thing happens 

in a LXDE session.

So I'm just throwing this question out in case anybody has had a similar

problem and might have some advice.

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## albright

problem still there with kernel 4.4.1

I upgraded 4.3.2 to 4.3.5 without the graphics glitch appearing so it

seems to be a 4.4 issue

nothing in logs or .xsessionerros and it happens with input

(mouse moving over window or sometimes keyboard press)

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## toralf

4.4.1 is out - if it isn't fixed there you might report this to the appropriate kernel mailing list.

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## albright

still happening on 4.4.2  - there is a kernel bug on this (I think it's the same

problem) 

some suggested enabling microcode - did not solve it for me

some suggested switching to uxa acceleration -- this seemed to greatly improve

but not eliminate the problem

typical errors around the time the screen temporarily blanks are this:

 *Quote:*   

> Feb 19 10:50:21 alatar kernel: [drm:intel_cpu_fifo_underrun_irq_handler] *ERROR* CPU pipe A FIFO underrun

 

back to 4.3.5 (not that there's anything wrong with that  :Smile:   )

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## albright

running 4.5.3 for a couple of hours without any screen blanking / blinking

hurray - I'll mark this solved

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## albright

spoke too soon - after rebooting today (after kde update) the problem

is back; really entirely mysterious

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## albright

FWIW (not much, I know) the problem was with the startech

displayport splitter; when I finally got proper cables to use

DP and HDMI everything worked ...

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