I got this Kingston Hyper-X performance DRAM on my stock i5-750, so this "1600mhz @ latency timing 9-9-9-27" will auto downgrade to "1333mhz @ latency timing 9-9-9-24" well that's what I read from the manual and CPU-Z, too.
The I saw something like "Programmable CAS Write Latency(CWL) = 7(DDR3-1333)" in the manual and wonder if I can tweak my latency timing a lil tighten?
The correct value is 1600mhz CL9. That is what it's manufacturer certified to run at. So for 1333mhz, you can definitely do CL8 and only maybe CL7, but you need to find out for yourself it it'll work or not. If it boots up you're probably ok but you should run either Memtest86+ or at least Prime95 blend.