If these are supposed to be optimized for Ethash, why only 5GB?

[gotminer]

https://news.bitcoin.com/nvidia-mining-gpu-to-be-launched-sooner-than-expected-reports/?utm_source=OneSignal%20Push&utm_medium=notification&utm_campaign=Push%20Notifications

"The P102-100 GPUs are similar to Nvidia’s P104-100 cards. They are equipped with CUDA cores 3200, with base clock at 1582 MHz. The physical memory is 5 GB in size, GDDR5X type, with 320-bit interface and 11 Gbps clock. The memory bandwidth is 400 GB/s. They come with PCIe Gen1 x4 bus support and two 8-pin PCI-E connectors. The maximum thermal design power is 250 Watt.

P102-100 will offer the following hashrates: ETH ~47 mhs; ZEC ~660 Sol/s; XMR ~879 hs."