We present a heterogeneous multi-accelerator cluster developed and deployed at NCSA. The cluster consists of 16 AMD dual-core CPU compute nodes each with four NVIDIA GPUs and one Xilinx FPGA. Cluster nodes are interconnected with both InfiniBand and Ethernet networks. The software stack
consists of standard cluster tools with the addition of accelerator-specific software packages and enhancements to the resource allocation and batch sub-systems. We highlight several HPC applications that have been developed and deployed on the cluster. We also present our Phoenix application
development framework that is meant to help with developing new applications and migrating existing legacy codes to heterogeneous systems.