RAM frequency doesn't really matter unless your application requires an extremely high amount of memory bandwidth, and I don't think
Blue Iris does.
Not that Blue Iris is light on memory.
My heavily loaded system (635 megapixels per second) is reading about 4-5 GB/s and writing about 4-5 GB/s to memory, when in service mode. With the GUI open on a 4K monitor it increases to about 7.5 GB/s read and 6 GB/s write. Trouble is, I don't know how close that is to the limit of a modern PC.