Some math:
DDR5 6000 is 3000mhz x 2 (double data rate) x 64 bits / 8 for bytes = 48000 /1000 = 48GB/s
DDR3 1866 is 933mhz x 2 x 64 / 8 / 1000 = 14.93GB/s. If you have 4 channels that is 4 x 14.93 = 59.72GB/s
Some math:
DDR5 6000 is 3000mhz x 2 (double data rate) x 64 bits / 8 for bytes = 48000 /1000 = 48GB/s
DDR3 1866 is 933mhz x 2 x 64 / 8 / 1000 = 14.93GB/s. If you have 4 channels that is 4 x 14.93 = 59.72GB/s