First you should run an AD Import of your computers.
Then you might run a report:
SELECT
[vRM_Computer_Item].[Guid],
[vRM_Computer_Item].[Name],
[Inv_OU_Membership].[Distinguished Name]
FROM
[vRM_Computer_Item]
LEFT OUTER JOIN [Inv_OU_Membership]
ON [vRM_Computer_Item].[Guid] = [Inv_OU_Membership].[_ResourceGuid]
WHERE
[Inv_OU_Membership].[Distinguished Name] NOT LIKE N'%OU=%'
OR
[Inv_OU_Membership].[Distinguished Name] IS NULL