The Jasper model is the last hardware revision of the phat models, before they introduced the Slims. They worked out a lot of the issues that plagued the earlier models, but the most notable improvment is the chipset. The Jasper uses a 65nm cpu and gpu, which was scaled down from 90nm originally on the older models. What does this mean? Well in short... smaller chip, less heat, less power, less chances of board warpage and cold solder joints under the gpu which is the leading cause of RROD.