não pode ativar o terceiro monitor com cartão integrado

Question

Bom dia para você!

Tenho algum problema com o meu terceiro monitor. Depois que eu entrei, ele mostra apenas 4 pontos e o logotipo Mint no centro

Linux Mint 18 Xfce. Eu tenho três monitores. Dois deles vem da minha Placa AMD dedicada (Radeon HD 6870), O terceiro vai do meu cartão Intel integrado. O system-display-manager vê todos eles e mostra-os como ativos.

Um dia deixei meu pc para dormir, e depois que eu o acordei o terceiro monitor apareceu ... Mas volta após o reinício.

lspci:

00:02.0 Display controller [0380]: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0102] (rev 09)
DeviceName:  Onboard IGD
Subsystem: Hewlett-Packard Company 2nd Generation Core Processor Family Integrated Graphics Controller [103c:2ab6]
Flags: bus master, fast devsel, latency 0, IRQ 28
Memory at fe000000 (64-bit, non-prefetchable) [size=4M]
Memory at b0000000 (64-bit, prefetchable) [size=256M]
I/O ports at f000 [size=64]
Capabilities: <access denied>
Kernel driver in use: i915
Kernel modules: i915

01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Barts XT [Radeon HD 6870] [1002:6738] (prog-if 00 [VGA controller])
Subsystem: Gigabyte Technology Co., Ltd Barts XT [Radeon HD 6870] [1458:21fa]
Flags: bus master, fast devsel, latency 0, IRQ 27
Memory at c0000000 (64-bit, prefetchable) [size=256M]
Memory at fe420000 (64-bit, non-prefetchable) [size=128K]
I/O ports at e000 [size=256]
Expansion ROM at 000c0000 [disabled] [size=128K]
Capabilities: <access denied>
Kernel driver in use: radeon
Kernel modules: radeon

lshw -class display

  *-display               
   description: VGA compatible controller
   product: Barts XT [Radeon HD 6870]
   vendor: Advanced Micro Devices, Inc. [AMD/ATI]
   physical id: 0
   bus info: pci@0000:01:00.0
   version: 00
   width: 64 bits
   clock: 33MHz
   capabilities: pm pciexpress msi vga_controller bus_master cap_list rom
   configuration: driver=radeon latency=0
   resources: irq:27 memory:c0000000-cfffffff memory:fe420000-fe43ffff ioport:e000(size=256) memory:c0000-dffff


  *-display
   description: Display controller
   product: 2nd Generation Core Processor Family Integrated Graphics Controller
   vendor: Intel Corporation
   physical id: 2
   bus info: pci@0000:00:02.0
   version: 09
   width: 64 bits
   clock: 33MHz
   capabilities: msi pm bus_master cap_list
   configuration: driver=i915 latency=0
   resources: irq:28 memory:fe000000-fe3fffff memory:b0000000-bfffffff ioport:f000(size=64)

Por favor, ajude!