Acer nitro 5 an515 52 ram bus July 8, 2019 16 32 64 128 Acer nitro 5 an515 ram upgrade Ram acer nitro 5 an515-54 Acer nitro 5 an515-42 disassembly Acer nitro 5 ram slots Acer nitro 5 an515-45-r21a