[docs/install/*_external.md] Improve PC3-8500 section and make it consistent

4 files changed, 36 insertions, 18 deletions

diff --git a/docs/install/r400_external.md b/docs/install/r400_external.md
index 19f673a6..c226c3aa 100644
--- a/docs/install/r400_external.md
+++ b/docs/install/r400_external.md
@@ -335,11 +335,16 @@ Not to be confused with wifi (wifi is fine).
 Memory
 ======
 
-You need DDR3 SODIMM PC3-8500 RAM installed, in matching pairs
-(speed/size). Non-matching pairs won't work. You can also install a
-single module (meaning, one of the slots will be empty) in slot 0.
+In DDR3 machines with Cantiga (GM45/GS45/PM45), northbridge requires sticks
+that will work as PC3-8500 (faster PC3/PC3L sticks can work as PC3-8500).
+Non-matching pairs may not work. Single module (meaning, one of the slots
+will be empty) will currently only work in slot 0.
 
-Make sure that the RAM you buy is the 2Rx8 density.
+NOTE: according to users reports, non matching pairs (e.g. 1+2 GiB) might
+work in some cases.
+
+Make sure that the RAM you buy is the 2Rx8 configuration when buying 4GiB sticks
+(In other words: maximum of 2GiB per rank, 2 ranks per card).
 
 [This page](http://www.forum.thinkpads.com/viewtopic.php?p=760721) might
 be useful for RAM compatibility info (note: coreboot raminit is
diff --git a/docs/install/t400_external.md b/docs/install/t400_external.md
index 362b2243..fe54af48 100644
--- a/docs/install/t400_external.md
+++ b/docs/install/t400_external.md
@@ -328,11 +328,16 @@ Not to be confused with wifi (wifi is fine).
 Memory
 ======
 
-You need DDR3 SODIMM PC3-8500 RAM installed, in matching pairs
-(speed/size). Non-matching pairs won't work. You can also install a
-single module (meaning, one of the slots will be empty) in slot 0.
+In DDR3 machines with Cantiga (GM45/GS45/PM45), northbridge requires sticks
+that will work as PC3-8500 (faster PC3/PC3L sticks can work as PC3-8500).
+Non-matching pairs may not work. Single module (meaning, one of the slots
+will be empty) will currently only work in slot 0.
 
-Make sure that the RAM you buy is the 2Rx8 density.
+NOTE: according to users reports, non matching pairs (e.g. 1+2 GiB) might
+work in some cases.
+
+Make sure that the RAM you buy is the 2Rx8 configuration when buying 4GiB sticks
+(In other words: maximum of 2GiB per rank, 2 ranks per card).
 
 [This page](http://www.forum.thinkpads.com/viewtopic.php?p=760721) might
 be useful for RAM compatibility info (note: coreboot raminit is
diff --git a/docs/install/t500_external.md b/docs/install/t500_external.md
index fc66387c..9433bd18 100644
--- a/docs/install/t500_external.md
+++ b/docs/install/t500_external.md
@@ -354,12 +354,16 @@ Not to be confused with wifi (wifi is fine).
 Memory
 ======
 
-DDR3 SO-DIMM sticks will work at PC3-8500 clock and voltage, so make sure that
-timings of sticks are matched while they operate at its frequency.
-Non-matching pairs won't work. You can also install a
-single module (meaning, one of the slots will be empty) in slot 0.
+In DDR3 machines with Cantiga (GM45/GS45/PM45), northbridge requires sticks
+that will work as PC3-8500 (faster PC3/PC3L sticks can work as PC3-8500).
+Non-matching pairs may not work. Single module (meaning, one of the slots
+will be empty) will currently only work in slot 0.
 
-Make sure that the RAM you buy has 2Rx8 arrangement when buying 4GiB modules.
+NOTE: according to users reports, non matching pairs (e.g. 1+2 GiB) might
+work in some cases.
+
+Make sure that the RAM you buy is the 2Rx8 configuration when buying 4GiB sticks
+(In other words: maximum of 2GiB per rank, 2 ranks per card).
 
 [This page](http://www.forum.thinkpads.com/viewtopic.php?p=760721) might
 be useful for RAM compatibility info (note: coreboot raminit is
diff --git a/docs/install/x200_external.md b/docs/install/x200_external.md
index 0b574a68..5c466b86 100644
--- a/docs/install/x200_external.md
+++ b/docs/install/x200_external.md
@@ -234,12 +234,16 @@ brings no benefits, while having many issues:
 Memory
 ======
 
-You need DDR3 SODIMM PC3-8500 RAM installed, in matching pairs
-(speed/size) as some non-matching pairs are known not to work.
-You can also install a single module (meaning, one of the
-slots will be empty) in slot 0.
+In DDR3 machines with Cantiga (GM45/GS45/PM45), northbridge requires sticks
+that will work as PC3-8500 (faster PC3/PC3L sticks can work as PC3-8500).
+Non-matching pairs may not work. Single module (meaning, one of the slots
+will be empty) will currently only work in slot 0.
 
-Make sure that the RAM you buy is the 2Rx8 density.
+NOTE: according to users reports, non matching pairs (e.g. 1+2 GiB) might
+work in some cases.
+
+Make sure that the RAM you buy is the 2Rx8 configuration when buying 4GiB sticks
+(In other words: maximum of 2GiB per rank, 2 ranks per card).
 
 In this photo, 8GiB of RAM (2x4GiB) is installed: