Update thermal.md

thermal.md

@@ -143,3 +143,30 @@ sudo cpupower --cpu all frequency-info | grep -e "current CPU" -e "The governor"
 
 ```
 
+# Undervoltage
+
+```sh
+sudo dnf install intel-undervolt
+sudo modprobe msr
+
+sudo dnf install msr-tools
+sudo modprobe msr
+
+echo "msr" | sudo tee /etc/modules-load.d/msr.conf
+sudo grubby --update-kernel=ALL --args="msr.allow_writes=on"
+```
+
+Check
+
+```sh
+lsmod | grep msr
+
+sudo dmesg | grep -i undervolt
+
+sudo rdmsr 0x150
+sudo rdmsr 0x150 -f 31:31
+# If this returns 1, undervolting is locked
+# If this returns 0, undervolting might be possible
+```
+
+