Compute intensive processing can be easily accelerated using processors with many cores such as GPUs. However, memory bandwidth limitation becomes serious year by year for memory bandwidth intensive applications such as sparse matrix vector multiplications (SpMV). In order to accelerate memory bandwidth intensive applications, we have proposed a memory system with additional functions of scattering and gathering. For the preliminary evaluation of our proposed system, we assumed that the throughput of the memory system was sufficient. In this paper, we propose a memory system with scattering and gathering using many narrow memory channels. We evaluate the feasible throughput of the proposed memory system based on DDR3 DRAM with the modified DRAMsim2 simulator. In addition, we evaluate the performance of SpMV using our method for the proposed memory system and a GPU. We have confirmed the proposed memory system has good performance and good stability for matrix shape variation using fewer pins for external memory.