How to get all rows that has same ID but diffrent value in other column?

I'm having a trouble writing a query in PostgreSQL. I have a View that contains IDs with subID. for example:

ID  quantity partID 
100   50       10
100   20       10
100   30       11
101   50       13
101   70       13
102   20       17

I want to get all rows that has same ID but different partIDs. for the given example I would like to get:

ID  quantity partID 
100   50       10
100   20       10
100   30       11

i tried this query query:

select id  ,quantity ,partid 
from A
group by id,quantity,partid
having count(id)>2
order by id

but it doesn't work. It accualty checks if ID appears in more than 2 rows... in the given example it will take ID 101 as well. I also don't know how to make it choose only partid which are diffrent per ID.