There is no cap for INT/DEX/STR/VIT or even a soft cap. The way S-E did it, is that for the main stat, you won't be able to get more unless you upgrade to the next ilvl pieces. For example if you have full DL or full HQ crafted set (both are ilvl70) they have the exact same main stat and you won't be able to get any more unless you acquire ilvl90 pieces which have more primary stat.