You just need to order Enum by its int value,
code:
@Html.DropDownListFor(m => m.TestEnumValue,Enum.GetValues(typeof(MyEnum))
.Cast<MyEnum>()
.OrderBy(e => (int)e)
.Select(e => new SelectListItem
{
Text = e.ToString(),
Value = ((int)e).ToString()
} ))
You also need to cast GetValues to get typed version: GetValues(typeof(MyEnum)).Cast<MyEnum>
result: