diff --git a/src/northbridge/intel/gm45/acpi.c b/src/northbridge/intel/gm45/acpi.c
index 8990c3b140..b90afca8a2 100644
--- a/src/northbridge/intel/gm45/acpi.c
+++ b/src/northbridge/intel/gm45/acpi.c
@@ -72,7 +72,8 @@ unsigned long acpi_fill_mcfg(unsigned long current)
 
 static unsigned long acpi_fill_dmar(unsigned long current)
 {
-	int me_active = (dev_find_slot(0, PCI_DEVFN(3, 0)) != NULL);
+	int me_active = (dev_find_slot(0, PCI_DEVFN(3, 0)) != NULL) &&
+		(pci_read_config8(dev_find_slot(0, PCI_DEVFN(3, 0)), PCI_CLASS_REVISION) != 0xff);
 	int stepping = pci_read_config8(dev_find_slot(0, PCI_DEVFN(0, 0)), PCI_CLASS_REVISION);
 
 	unsigned long tmp = current;
diff --git a/src/northbridge/intel/gm45/iommu.c b/src/northbridge/intel/gm45/iommu.c
index 10548f48a3..0c3c18ef0c 100644
--- a/src/northbridge/intel/gm45/iommu.c
+++ b/src/northbridge/intel/gm45/iommu.c
@@ -40,6 +40,8 @@ void init_iommu()
 	}
 	if (me_active) {
 		MCHBAR32(0x10) = IOMMU_BASE3 | 1; /* ME  @ 0:3.0-3 */
+	} else {
+		MCHBAR32(0x10) = 0; /* disable IOMMU for ME */
 	}
 	MCHBAR32(0x20) = IOMMU_BASE4 | 1; /* all other DMA sources */