The motherboard specs page state that ECC ram is not supported. Stick to 16GB's of DDR3 memory. 32GB across 2 sticks were impossible to find even when the platform was somewhat new. I doubt they were made though.
but it seems you need to find "AMD Only" ddr3. it should be 2Rx8 composed of 8GB per ranks. I dont really know if such thing like 16gb per dimm for amd only platform exists..