external monitor and strange fan behavior

laptop 7720se bios A14/A15 win 8

Do you ever notice that connecting a second monitor to laptop via vga or hdmi drives fan to 2600rpm after a while even in idle mode with cpu temps at 30-35? 

the fan speed stays at 2600rpm even if cpu temps drops to 30c-40c in idle mode and wont stop.

when i dissconect the external monitor and restarts the laptop or wake up it from sleep the fan works normal as it should. 

goes up when it should (lets say >55c) and stops when it should.

connecting again the external monitor, wait for a while without do nothing (cpu temps around 35c) and the fan from 0 goes to 2600rpm

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is it so stressful for the hd4000 to cope with 2 monitors (with different resolutions) and make the fan spinning at 2600rpm ?

I m sure that the cpu temps plays no role

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note   that in HWinFO64 the GPU temps under ACPI (not the nvidia temp) drops to 30-34c but the fan wont stop in idle state.