diff --git a/configs/sama5d3x-ek/README.txt b/configs/sama5d3x-ek/README.txt
index aa455cda9ea..dd713ac9c13 100644
--- a/configs/sama5d3x-ek/README.txt
+++ b/configs/sama5d3x-ek/README.txt
@@ -1011,7 +1011,11 @@ Configurations
          CONFIG_MTD=y                          : Enable MTD support
          CONFIG_MTD_AT25=y                     : Enable the AT25 driver
          CONFIG_AT25_SPIMODE=0                 : Use SPI mode 0
-         CONFIG_AT25_SPIFREQUENCY=20000000     : Use SPI frequency 20MHz
+         CONFIG_AT25_SPIFREQUENCY=10000000     : Use SPI frequency 10MHz
+
+       The AT25 is capable of higher SPI rates than this.  I have not
+       experimented a lot, but at 20MHz, the behavior is not the same with
+       all CM modules.  This lower rate gives more predictable performance.
 
        Application Configuration -> NSH Library
          CONFIG_NSH_ARCHINIT=y                 : NSH board-initialization
@@ -1490,7 +1494,11 @@ Configurations
          CONFIG_MTD=y                          : Enable MTD support
          CONFIG_MTD_AT25=y                     : Enable the AT25 driver
          CONFIG_AT25_SPIMODE=0                 : Use SPI mode 0
-         CONFIG_AT25_SPIFREQUENCY=20000000     : Use SPI frequency 20MHz
+         CONFIG_AT25_SPIFREQUENCY=10000000     : Use SPI frequency 10MHz
+
+       The AT25 is capable of higher SPI rates than this.  I have not
+       experimented a lot, but at 20MHz, the behavior is not the same with
+       all CM modules.  This lower rate gives more predictable performance.
 
        Application Configuration -> NSH Library
          CONFIG_NSH_ARCHINIT=y                 : NSH board-initialization
diff --git a/configs/sama5d3x-ek/demo/defconfig b/configs/sama5d3x-ek/demo/defconfig
index bc6618345d1..90cc043debf 100644
--- a/configs/sama5d3x-ek/demo/defconfig
+++ b/configs/sama5d3x-ek/demo/defconfig
@@ -421,7 +421,7 @@ CONFIG_MTD=y
 # CONFIG_MTD_AT24XX is not set
 CONFIG_MTD_AT25=y
 CONFIG_AT25_SPIMODE=0
-CONFIG_AT25_SPIFREQUENCY=20000000
+CONFIG_AT25_SPIFREQUENCY=10000000
 # CONFIG_MTD_AT45DB is not set
 # CONFIG_MTD_M25P is not set
 # CONFIG_MTD_SMART is not set