Why was RDRAM so expensive? Rambus asserts a royalty charge of 1% for SDRAM, 3% for DDR, and 2-5% for RDRAM. This means Rambus will get that percentage of total sales from each memory manufacturer. This primarily stems from manufacturing costs. Initially, Samsung and other manufacturers had to retool and gear up to produce Rimms(Rambus inline memory modules). This was costly. Rambus prices now are alot cheaper now then when it was first intoduced.