-#define G4x_GMCH_SIZE_VT_1M (0x9 << 8)
-#define G4x_GMCH_SIZE_VT_1_5M (0xa << 8)
-#define G4x_GMCH_SIZE_VT_2M (0xc << 8)
+#define G4x_GMCH_SIZE_VT_EN (0x8 << 8)
+#define G4x_GMCH_SIZE_VT_1M (G4x_GMCH_SIZE_1M | G4x_GMCH_SIZE_VT_EN)
+#define G4x_GMCH_SIZE_VT_1_5M ((0x2 << 8) | G4x_GMCH_SIZE_VT_EN)
+#define G4x_GMCH_SIZE_VT_2M (G4x_GMCH_SIZE_2M | G4x_GMCH_SIZE_VT_EN)