I have seen that page on ECS website.
but i know that some main-boards from other brands with the same spec. can support this CPU. for example gigabyte GA-G41M-ES2H (rev. 1.0) or GA-G41MT-ES2L (rev. 1.1).
I want to know why this CPU is not in that page on ECS website.
some times manufacturers only list parts that they have tested.
U can't compare an ECS mobo with a Gigabyte mobo is like compare a CRT TV against a LED 3D TV.
The support CPU depends purely of the manufacturer and the BIOS that they release to support that specific CPU. Like u say, the Gigabyte support that CPU but because the Gigabyte engineers worked in a BIOS version that support that CPU, ECS don't do it.