Add message about needing to export display on linux.
diff --git a/README b/README
index 41b60c1..86ee8e5 100644
--- a/README
+++ b/README
@@ -189,6 +189,11 @@ cgminer -o http://pool:port -u username -p password -I 9 --auto-fan --auto-gpu -
READ WARNINGS AND DOCUMENTATION BELOW ABOUT OVERCLOCKING
+On Linux you virtually always need to export your display settings before
+starting to get all the cards recognised and/or temperature+clocking working:
+
+export DISPLAY=:0
+
---
WHILE RUNNING: