Sub maj()
Dim T As Variant, Rng As Range, i As Long
With Sheets("Feuil1")
Set Rng = .Range("$C$5")
T = .Range(Rng, .Cells(.Rows.Count, Rng.Column).End(3))
End With
For i = LBound(T, 1) To UBound(T, 1)
T(i, 1) = UCase(T(i, 1))
Next i
Rng.Resize(UBound(T, 1), 1) = T
End Sub