CoreElec on 800x640

Hi To all
I would like to run CoreElec hosted on Odroid C2 with the VU5. It’s working with 800x640 only.
I done some test with boot.ini like theses settings: dvi mode, 800x640, etc.
But the screen stay white.
Plug to a TV, the kodi works with a compliance screen definition.

Can i do that for working only with VU5 ?
I just say i need to get hmdi audio connect to a hdmi splitter.