I5 2500k IGPU use via external GPU
i want to use i5 2500k IGPU via external GPU, but my mothrboard didn't have any display port(DVI,VGA,HDMI). main aim to use IGPU is to save power by switch off external GPU
From your description it is impossible to do. When the graphics card is powered down none of the video ports are active.
The motherboard must have video ports and a BIOS option that allows the iGPU to be set as the primary GPU. You will also need to install Lucid Logix Virtu which handles the powering down of the discrete graphics card when it's not needed.
Lucid VIRTU i-Mode
i-Mode provides near zero performance overhead on 3D games, when no 3D games is used, the integrated CPU/GPU special features and power saving options are enabled.
To use Lucid VIRTU in i-Mode, display must be connected to mainboard video output.
Lucid VIRTU d-Mode
d-Mode is provided for demanding 3D gamers to achieve uncompromised 3D performance of the discrete GPU installed in the system. In this mode, Virtu software allows user to utilize the special features of the Integrated GPU, while the display is connected to discrete GPU.
As 3D graphics performance is merely the same in i-Mode and d-Mode it is strongly recommended to connect the display to the integrated GPU, allowing power saving.
To use Lucid Virtu in d-Mode, the display must be connected to graphics card installed in the system.
This mode would be used if you want to use the Sandy/Ivy Bridge CPU's Quick Sync Video feature to enable fast video encoding. The iGPU isn't used for displaying any graphics and the discrete graphics card does not get powered down like it does in i-Mode so you don't get the power savings.