diff --git a/src/northbridge/intel/gm45/northbridge.c b/src/northbridge/intel/gm45/northbridge.c
index e14f843..405eb5d 100644
--- a/src/northbridge/intel/gm45/northbridge.c
+++ b/src/northbridge/intel/gm45/northbridge.c
@@ -13,6 +13,7 @@
  * GNU General Public License for more details.
  */
 
+#include <cbmem.h>
 #include <console/console.h>
 #include <arch/io.h>
 #include <stdint.h>
@@ -72,7 +73,7 @@
 static void mch_domain_read_resources(struct device *dev)
 {
 	u64 tom, touud;
-	u32 tomk, tolud, uma_sizek = 0;
+	u32 tomk, tolud, uma_sizek = 0, delta_cbmem;
 	u32 pcie_config_base, pcie_config_size;
 
 	/* Total Memory 2GB example:
@@ -138,6 +139,15 @@
 	tomk -= tseg_sizek;
 	uma_sizek += tseg_sizek;
 
+	/* cbmem_top can be shifted downwards due to alignment.
+	   Mark the region between cbmem_top and tomk as unusable */
+	delta_cbmem = tomk - ((uint32_t)cbmem_top() >> 10);
+	tomk -= delta_cbmem;
+	uma_sizek += delta_cbmem;
+
+	printk(BIOS_DEBUG, "Unused RAM between cbmem_top and TOM: 0x%xK\n",
+	       delta_cbmem);
+
 	printk(BIOS_INFO, "Available memory below 4GB: %uM\n", tomk >> 10);
 
 	/* Report the memory regions */
diff --git a/src/northbridge/intel/i945/northbridge.c b/src/northbridge/intel/i945/northbridge.c
index 110a9ef..de55cc35 100644
--- a/src/northbridge/intel/i945/northbridge.c
+++ b/src/northbridge/intel/i945/northbridge.c
@@ -13,6 +13,7 @@
  * GNU General Public License for more details.
  */
 
+#include <cbmem.h>
 #include <console/console.h>
 #include <arch/io.h>
 #include <stdint.h>
@@ -59,7 +60,7 @@
 
 static void mch_domain_read_resources(struct device *dev)
 {
-	uint32_t pci_tolm, tseg_sizek;
+	uint32_t pci_tolm, tseg_sizek, cbmem_topk, delta_cbmem;
 	uint8_t tolud;
 	uint16_t reg16;
 	unsigned long long tomk, tomk_stolen;
@@ -104,6 +105,16 @@
 	tseg_memory_base = tomk_stolen * 1024ULL;
 	tseg_memory_size = tseg_sizek * 1024ULL;
 
+	/* cbmem_top can be shifted downwards due to alignment.
+	   Mark the region between cbmem_top and tomk as unusable */
+	cbmem_topk = ((uint32_t)cbmem_top() >> 10);
+	delta_cbmem = tomk_stolen - cbmem_topk;
+	tomk_stolen -= delta_cbmem;
+
+	printk(BIOS_DEBUG, "Unused RAM between cbmem_top and TOM: 0x%xK\n",
+	       delta_cbmem);
+
+
 	/* The following needs to be 2 lines, otherwise the second
 	 * number is always 0
 	 */
@@ -115,6 +126,7 @@
 	ram_resource(dev, 4, 768, (tomk - 768));
 	uma_resource(dev, 5, uma_memory_base >> 10, uma_memory_size >> 10);
 	mmio_resource(dev, 6, tseg_memory_base >> 10, tseg_memory_size >> 10);
+	uma_resource(dev, 7, cbmem_topk, delta_cbmem);
 }
 
 static void mch_domain_set_resources(struct device *dev)
diff --git a/src/northbridge/intel/pineview/northbridge.c b/src/northbridge/intel/pineview/northbridge.c
index 4775b15..2647bcc 100644
--- a/src/northbridge/intel/pineview/northbridge.c
+++ b/src/northbridge/intel/pineview/northbridge.c
@@ -14,6 +14,7 @@
  * GNU General Public License for more details.
  */
 
+#include <cbmem.h>
 #include <console/console.h>
 #include <arch/io.h>
 #include <stdint.h>
@@ -55,7 +56,7 @@
 {
 	u64 tom, touud;
 	u32 tomk, tolud, tseg_sizek;
-	u32 pcie_config_base, pcie_config_size;
+	u32 pcie_config_base, pcie_config_size, cbmem_topk, delta_cbmem;
 	u16 index;
 	const u32 top32memk = 4 * (GiB / KiB);
 
@@ -100,6 +101,16 @@
 	/* Subtract TSEG size */
 	tseg_sizek = gtt_basek - tseg_basek;
 	tomk -= tseg_sizek;
+	printk(BIOS_DEBUG, "TSEG decoded, subtracting %dM\n", tseg_sizek >> 10);
+
+	/* cbmem_top can be shifted downwards due to alignment.
+	   Mark the region between cbmem_top and tomk as unusable */
+	cbmem_topk = (uint32_t)cbmem_top() >> 10;
+	delta_cbmem = tomk - cbmem_topk;
+	tomk -= delta_cbmem;
+
+	printk(BIOS_DEBUG, "Unused RAM between cbmem_top and TOMK: 0x%xK\n",
+	       delta_cbmem);
 
 	/* Report the memory regions */
 	ram_resource(dev, index++, 0, 640);
@@ -107,6 +118,7 @@
 	reserved_ram_resource(dev, index++, tseg_basek, tseg_sizek);
 	reserved_ram_resource(dev, index++, gtt_basek, gsm_sizek);
 	reserved_ram_resource(dev, index++, igd_basek, gms_sizek);
+	reserved_ram_resource(dev, index++, cbmem_topk, delta_cbmem);
 
 	/*
 	 * If > 4GB installed then memory from TOLUD to 4GB
diff --git a/src/northbridge/intel/x4x/northbridge.c b/src/northbridge/intel/x4x/northbridge.c
index d1926b2..bc7a5b3 100644
--- a/src/northbridge/intel/x4x/northbridge.c
+++ b/src/northbridge/intel/x4x/northbridge.c
@@ -14,6 +14,7 @@
  * GNU General Public License for more details.
  */
 
+#include <cbmem.h>
 #include <console/console.h>
 #include <arch/io.h>
 #include <stdint.h>
@@ -35,7 +36,7 @@
 {
 	u8 index, reg8;
 	u64 tom, touud;
-	u32 tomk, tseg_sizek = 0, tolud;
+	u32 tomk, tseg_sizek = 0, tolud, delta_cbmem;
 	u32 pcie_config_base, pcie_config_size;
 	u32 uma_sizek = 0;
 
@@ -100,6 +101,15 @@
 
 	printk(BIOS_DEBUG, "%dM\n", tseg_sizek >> 10);
 
+	/* cbmem_top can be shifted downwards due to alignment.
+	   Mark the region between cbmem_top and tomk as unusable */
+	delta_cbmem = tomk - ((uint32_t)cbmem_top() >> 10);
+	tomk -= delta_cbmem;
+	uma_sizek += delta_cbmem;
+
+	printk(BIOS_DEBUG, "Unused RAM between cbmem_top and TOM: 0x%xK\n",
+	       delta_cbmem);
+
 	printk(BIOS_INFO, "Available memory below 4GB: %uM\n", tomk >> 10);
 
 	/* Report the memory regions */