Yeah, cas 3. It's 6 layer memory from a company called pmi at newegg. It was all I could afford at the time. May have to sell it and get a better brand if it won't run at 400 speed. I downloaded the is7 manual, but they don't list the cas settings. I wrote msi and abit tech support, but all I got was an automated response with a bunch of useless faqs. My old msi board only offers cas 2 or 2.5 settings. This memory will only run at 360 at case 2 or 2.5.