It is coming from my motherboard, what should i do?
Try to tighten all of the screws that attach the mobo to the case. On a standard ATX mobo there are 9 hold down screws in 3 rows of 3 each. Since yours is an Acer, it is prolly a proprietary MOBO and may have more or less screws, arranged differently.
If that doesn't work, you may have a defective component on the MOBO, which would be difficult to repair.
Did you try the hose? I find it hard to believe that the whole MOBO is making noise. It almost certainly has to be a single component buzzing.
Yogi