How to check RAM timings in linux?

Memtest will show you the timings and I found on the ubuntuforums that i2c-tools will give you what you're looking for with these commands:

sudo modprobe eeprom    
decode-dimms

This worked for me:

sudo aptitude install i2c-tools
sudo modprobe eeprom
sudo modprobe at24
sudo modprobe i2c-i801
sudo modprobe i2c-amd-mp2-pci
sudo modprobe ee1004
decode-dimms

decode-dimms needs the correct module to be loaded to be able to read the DIMMs. It is unclear to me exactly which one worked for me, but I guess it depends on the chipset in your machine.

You can get information about the memory with:

lshw -C memory

In particular, you can get the clock speed and latency with:

lshw -C memory | grep clock