On 20 May, Kevin McGregor wrote:

Sorry this is not a *nix question, but here goes:

Should there be any problem mixing two DDR2-667 DIMMs (CAS 4-4-4-12) with two other DDR2-667 DIMMs (CAS 5-5-5-15)? Would you expect problems, or should the system just use the slower of the speeds?

Works fine. Will use slowest speed. If dual channel (almost certainly is), try to match the pairs in the proper banks.

Contrary to popular belief, you can very easily mix & match speeds in the same DDR spec. For example, most DDR1 systems that take 266 or 333 will easily take 400 which is cheaper. Same with DDR2. So buy the cheapest one that is >= the speed your board supports.

The only time this may not work is if you're doing weird overclocking stuff.