The 2TB model of the WD Black SN850X that was used for this review arrived with two 1TB blocks and this is what allowed this good-sized capacity drive to remain single-sided. The 4TB model unsurprisingly needs to spread itself out a bit and also is the only capacity in the SN850X not...
WD can use 512Gb dies for lower capacities, but 1Tb dies are necessary to keep the drive single-sided at 4TB. This indicates that both the 2TB and 4TB SKUs have the ideal amount of total dies, that is thirty-two (four per channel), for peak performance. BiCS5 didn’t quite pan out...