The Samsung DIMMs can be considered a mainstream product, as they are not rated for extremely fast timings anyway. Unfortunately, Samsung neglected to put the maximum theoretical timings on the product sticker, which makes it rather difficult to determine the ideal values without data from the SPD.
We were disappointed that the modules would not start up at the CL3-3-3-8 stored in the SPD, but they eventually did so at CL4-4-4-11. The more the speed is notched up, the more conservative the timings have to be: CL5-4-5-11 is required at DDR2-667 and DDR2-710. In the latter case we experienced a crash; however, we were unable to attribute this unequivocally to the DIMMs. We decided that the principle of "innocent until proven guilty" applies here, as we could not replicate the effect.