Try this:
Select Top (1000000) tblAssets.AssetID,
tblAssets.AssetName,
tblAssets.Domain,
tblAssets.Username,
tblAssets.Userdomain,
Coalesce(tsysOS.Image, tsysAssetTypes.AssetTypeIcon10) As icon,
tblAssets.IPAddress,
tsysIPLocations.IPLocation,
tblAssetCustom.Manufacturer,
tblAssetCustom.Model,
tsysOS.OSname As OS,
tblAssets.SP,
tblAssets.Lastseen As [Last successful scan],
tblAssets.Lasttried As [Last scan attempt],
tblVolume.Name As VolumeName,
tblVolume.DriveLetter,
tblVolume.Label As LogicalDiskName,
Case tblVolume.DriveType
When 0 Then 'Unknown'
When 1 Then 'No Root Directory'
When 2 Then 'Removable Disk'
When 3 Then 'Local Disk'
When 4 Then 'Network Drive'
When 5 Then 'Compact Disk'
Else 'RAM Disk'
End As DriveType,
Cast(tblVolume.FreeSpace / 1024 / 1024 / 1024 As numeric) As FreeGB,
tblVolume.Capacity,
Cast(tblVolume.Capacity / 1024 / 1024 / 1024 As numeric) As TotalSizeGB,
tblVolume.Automount,
tblVolume.BlockSize,
tblVolume.Compressed,
tblVolume.DeviceID,
tblVolume.DirtyBitSet,
tblVolume.ErrorCleared,
tblVolume.ErrorDescription,
tblVolume.ErrorMethodology,
tblVolume.FileSystem,
tblVolume.IndexingEnabled,
tblVolume.PageFilePresent,
tblVolume.SupportsDiskQuotas,
tblVolume.SupportsFileBasedCompression,
tblVolume.Lastchanged
From tblAssets
Inner Join tblAssetCustom On tblAssets.AssetID = tblAssetCustom.AssetID
Inner Join tsysAssetTypes On tsysAssetTypes.AssetType = tblAssets.Assettype
Inner Join tblVolume On tblAssets.AssetID = tblVolume.AssetID
Inner Join tsysIPLocations On tsysIPLocations.LocationID =
tblAssets.LocationID
Left Outer Join tsysOS On tblAssets.OScode = tsysOS.OScode
Inner Join tblState On tblState.State = tblAssetCustom.State
Where tblState.Statename = 'Active' And Coalesce(tblVolume.DriveLetter, '') = '' and Coalesce(tblVolume.Label, '') = ''
Order By tblAssets.Domain,
tblAssets.AssetName,
VolumeName