I'm confused with relation between frequency and timing information when buying DDR3 RAM modules. I have OCZ DDR3 modules which should have 1600MHz frequency and CAS 7-7-7-20. If I use these modules and do not specify any configuration in BIOS they really have CAS 7-7-7-20 but frequency is set to default 1066 (system with Intel i7 920). If I manually change frequency to 1600 the CAS is 9-9-9-24. If I manually change both frequency and timing information to 1600 with 7-7-7-20 my system will not boot because of overclocking failure. I do not want to overclock the system. I just thought that memory should run on 1600MHz with CAS 7-7-7-20.

So are these values related or they only shows best values which memory modules can achive but these values don't have to be achived together? If these values are not related which one is more important?


Motherboard is Asus P6T Deluxe V2. I see that description shows that 1600MHz modules are supported only with overclocking.

Question about importance of values is already obsolete because by playing with different settings in BIOS I found that my motherboard uses only 4 of 6 RAM modules if frequency is set to 1600MHz.


The JEDEC standard for DDR3 specifies 1600 MHz at 8-8-8 (CL-tRCD-tRP). Running anything with timings lower than that is considered overclocking. Your RAM can be run at that speed, but the other components inside your PC might not.

If your mobo supports Intel XMP, try using that. If you still can't boot, then just run it at 9-9-9-24. You'll not likely notice any difference from the timing boost.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.