Intel socket LGA1155 CPUs have an embedded memory controller, meaning that it is the processor, not the chipset, that defines what memory technologies and the maximum amount of memory you can have. The motherboard, however, may have a limitation as to how much memory can be installed.
The integrated memory controller from socket LGA1155 processors support only DDR3 memories up to 1,333 MHz under dual-channel architecture.
The ASRock H61M/U3S3 has two memory sockets, supporting up to 8 GB each, for 16 GB total.
You must install two identical memory modules in order to enable the dual-channel architecture and achieve the maximum performance of which your system is capable.