Primeiro para apurar o motivo é necessários saber seu hardware, irei aproveitar e pedir essa informação para que quem é mais experiente posteriormente possa lhe ajudar.
Coloque o seguinte comando:
sudo apt update ; sudo apt install inxi
Depois ponha esse:
inxi -FxZ
Irá aparecer algo assim:
System: Host: Rafael-desktop Kernel: 4.4.0-38-generic x86_64 (64 bit gcc: 5.4.0)
Desktop: Cinnamon 3.0.7 (Gtk 3.18.9-1ubuntu3.1)
Distro: Ubuntu 16.04 xenial
Machine: Mobo: N/A model: Phitronics H55-M
Bios: American Megatrends v: P1.00 date: 10/20/2010
CPU: Dual core Intel Core i5 650 (-HT-MCP-) cache: 4096 KB
flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 12850
clock speeds: max: 3212 MHz 1: 3212 MHz 2: 3212 MHz 3: 3212 MHz
4: 3212 MHz
Graphics: Card: NVIDIA GT218 [GeForce 210] bus-ID: 05:00.0
Display Server: X.Org 1.18.3 drivers: nvidia (unloaded: fbdev,vesa,nouveau)
Resolution: 1920x1080@60.00hz
GLX Renderer: GeForce 210/PCIe/SSE2
GLX Version: 3.3.0 NVIDIA 340.96 Direct Rendering: Yes
Audio: Card-1 Intel 5 Series/3400 Series High Definition Audio
driver: snd_hda_intel bus-ID: 00:1b.0
Card-2 NVIDIA High Definition Audio Controller
driver: snd_hda_intel bus-ID: 05:00.1
Sound: Advanced Linux Sound Architecture v: k4.4.0-38-generic
Network: Card: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
driver: r8169 v: 2.3LK-NAPI port: d800 bus-ID: 01:00.0
IF: enp1s0 state: up speed: 100 Mbps duplex: full
mac: 00:25:22:92:c2:95
Drives: HDD Total Size: 500.1GB (13.1% used)
ID-1: /dev/sda model: WDC_WD5000AAKX size: 500.1GB
Partition: ID-1: / size: 455G used: 56G (13%) fs: ext4 dev: /dev/sda1
ID-2: swap-1 size: 4.28GB used: 0.00GB (0%) fs: swap dev: /dev/dm-0
ID-3: swap-2 size: 0.52GB used: 0.09GB (18%) fs: swap dev: /dev/zram0
ID-4: swap-3 size: 0.52GB used: 0.09GB (18%) fs: swap dev: /dev/zram1
ID-5: swap-4 size: 0.52GB used: 0.09GB (18%) fs: swap dev: /dev/zram2
ID-6: swap-5 size: 0.52GB used: 0.09GB (18%) fs: swap dev: /dev/zram3
RAID: No RAID devices: /proc/mdstat, md_mod kernel module present
Sensors: System Temperatures: cpu: 40.0C mobo: N/A gpu: 0.0:59C
Fan Speeds (in rpm): cpu: N/A
Info: Processes: 227 Uptime: 1:26 Memory: 3233.3/3940.5MB
Init: systemd runlevel: 5 Gcc sys: 5.4.0
Client: Shell (bash 4.3.461) inxi: 2.2.35
Copie e cole aqui no fórum, posteriormente virá membros mais experientes para ajuda-lo.
A propósito as informações para lhe ajudar são provenientes do membro creto, caso tenha dificuldades para entender nesse tópico ele explica melhor:
http://ubuntuforum-br.org/index.php/topic,120796.0.html