(Reuters) - Amazon.com Inc said on Tuesday it had designed a more powerful data center processor chip, as it looks to pose a serious challenge to the domination of market leaders Intel Corp and Advanced Micro Devices Inc .The AWS Graviton 2 processor, which is estimated to be seven times faster than its previous chip, uses technology from Softbank Group Corp-owned Arm Holdings. Reuters reported last week that Amazon was looking to design a data center processor chip to power its cloud..