The Strix board is pretty bad hardware wise compared to some others.
The best seems to be the MSI B450 Tomahawk, however like another poster said above its having a lot of issues with the BIOS stability. Reading comments on Reddit people seem to be saying that MSI support is telling them to return the boards for the Tomahawk MAX models which come pre-built with Zen2/Ryzen3xxx support.
Not sure if the Max boards have reached Malaysia though.
The 3600 is a far better buy than the i5, the extra cores come in handy even if you only use the computer for gaming since you'll have stuff running in the background anyway. The computer will remain more responsive.
Anyway not sure if a 120mm radiator will perform better than a mid range air cooler? Check that out a bit more, a 240mm AIO might be a better idea.
new budget ryzen pc build comment, vs intel