GPU seems to cause problems

[Robert24]

Hello everyone!

First of all, I'm not sure if this is the right forum to ask questions. My question is related to my GPU, so maybe it goes into something more hardware oriented. I read here:
https://www.kubuntuforums.net/showth...Before-Posting
that there is a forum for hardware but I couldn't find it...

If someone is able to move my tread to the right place (if needed), I would be grateful.

My question is the following: on my computer I have two graphic cards. An Intel and an NVidia. When I activate the NVidia one with NVidia X Server Setting, I start observing some little white cube appearing and disappearing near the pointer of my mouse sometimes the cube is filled by something which is on the screen (or was). This problem doesn't occur when I use the Intel card. I recently reinstalled kubuntu and I have this problem only since then. I don't remember which driver I was using at the time, but I think that I am currently using the ``recommended one" since it is what the driver manager recommends me:



I can live with this even if it is a bit annoying, but I would like to know it the performance of my graphic card are also affected, in term of computation time.

I put here a print screen where you can see by yourself (note that in this case the pointer was a bit further away from this cube):


These cubes disappear when I move the pointer, but they are a bit annoying and I'm afraid that it may indicate that my NVidia card is not working properly.

Concerning my system and my machine, here is the output from inxi:

System:    Host: aritz-ThinkPad-T460p Kernel: 4.13.0-32-generic x86_64 (64 bit gcc: 5.4.0)
         Desktop: KDE Plasma 5.5.5 (Qt 5.5.1) Distro: Ubuntu 16.04 xenial
Machine:   System: LENOVO (portable) product: 20FXS0XY00 v: ThinkPad T460p                                                            
         Mobo: LENOVO model: 20FXS0XY00 v: SDK0J40697 WIN Bios: LENOVO v: R07ET69W (2.09 ) date: 07/28/2016                         
CPU:       Quad core Intel Core i7-6700HQ (-HT-MCP-) cache: 6144 KB                                                                   
         flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 20736                                                          
         clock speeds: max: 3500 MHz 1: 2600 MHz 2: 2600 MHz 3: 2600 MHz 4: 2600 MHz 5: 2600 MHz 6: 2600 MHz                        
         7: 2600 MHz 8: 2600 MHz                                                                                                    
Graphics:  Card-1: Intel Skylake Integrated Graphics bus-ID: 00:02.0                                                                  
         Card-2: NVIDIA GM108M [GeForce 940MX] bus-ID: 02:00.0                                                                      
         Display Server: X.Org 1.19.5 driver: nvidia Resolution: 2560x1440@60.00hz                                                  
         GLX Renderer: GeForce 940MX/PCIe/SSE2 GLX Version: 4.5.0 NVIDIA 384.111 Direct Rendering: Yes
Audio:     Card Intel Sunrise Point-H HD Audio driver: snd_hda_intel bus-ID: 00:1f.3
         Sound: Advanced Linux Sound Architecture v: k4.13.0-32-generic
Network:   Card-1: Intel Ethernet Connection (2) I219-LM driver: e1000e v: 3.2.6-k bus-ID: 00:1f.6
         IF: enp0s31f6 state: down mac: <filter>
         Card-2: Intel Wireless 8260 driver: iwlwifi bus-ID: 03:00.0
         IF: wlp3s0 state: up mac: <filter>
Drives:    HDD Total Size: 512.1GB (16.3% used) ID-1: /dev/sda model: SAMSUNG_MZ7LN512 size: 512.1GB temp: 34C
Partition: ID-1: / size: 24G used: 7.9G (35%) fs: ext4 dev: /dev/sda5
         ID-2: /home size: 159G used: 66G (44%) fs: ext4 dev: /dev/sda6
         ID-3: swap-1 size: 4.29GB used: 0.00GB (0%) fs: swap dev: /dev/sda7
RAID:      No RAID devices: /proc/mdstat, md_mod kernel module present
Sensors:   System Temperatures: cpu: 38.0C mobo: N/A gpu: 0.0:39C
         Fan Speeds (in rpm): cpu: 1953
Info:      Processes: 232 Uptime: 51 min Memory: 2104.3/15906.1MB Init: systemd runlevel: 5 Gcc sys: 5.4.0
         Client: Shell (bash 4.3.481) inxi: 2.2.35

Thanks in advance

[oshunluvr]

Robert24: Each version of Kubuntu that has a subforum has a "Hardware Support" section. This helps everyone identify your version of Kubuntu since there are always several valid versions alive at any given time. I detected in your previous posts that you were using 16.04 so I moved this here. If I was mistaken, let me know and I'll place it properly.

[Robert24]

Thanks a lot for doing this. Now I understand better how this all work.

In between I found the a workaround to my problem here:
https://bugs.launchpad.net/ubuntu/+s...4/+bug/1684240
which is:
``My workaroud for this Problem: Go to KDE System Settings -> Display and Monitor -> Compositor (left side) -> set "Rendering Backend" to XRender"

Have a nice day.

[oshunluvr]

I saw several reports of this varying with driver versions and Xorg versions. As you get more comfortable with Linux, you might consider attempting a driver change to see if things improve. On the other hand, if your setup is working to your liking, no need to change anything.

[Robert24]

Thing is, I don't know exactly what to choose. Some people in the link that I mentioned above said that using Nouveau driver instead of the NVidia ones were solving this specific problem.

But for me it is quite important that the GPU works properly, and I have no idea how these drivers affect (or don't affect) the performances of the graphical card. Do you know if there is a way to measure if a card is working properly or not, in term of performance? I need to do some computation for some image recognition tasks (neural networks/deep learning), and a good GPU is really required.

For now as I don't see any obvious problem anymore, I will stick with my configuration since it's working.