never use ram with different bus speeds! Never Ever use set of RAMs with non-identical CAS latency speeds!
That is a very very huge mistake, And a certain recipe for disaster and unstable or unusable pc. Also, you will surely doom your pc!

most crucial sync are the ram set up. sometimes even ram with the same exact specs, i mean all specs exactly the same, but the only thing different is the brand...AND you will still get that same exact error you are getting.

rule of thumb on using ram on your mobo/pc.
bus speed, brand, RAM voltage, CAS, clock speeds should all match