The launch of the Snapdragon 670 has not been officially confirmed, however, there are rumours about it. Some reports say that Xiaomi will come out with two Snapdragon 670 phones this year.
The info comes from Mishaal Rahman of XDA Developers, who posted in a tweet that Xiaomi is developing two phones like this, whose codenames are “Comet” and “Serius”.
Xiaomi has (at least) 2 devices with the unannounced Qualcomm Snapdragon 670 (sdm670) in the works: "comet" and "sirius".
Also confirms @rquandt's report which showed sdm670's little cluster has 6 cores and the big cluster has 2 cores. (targetconfig.xml in /vendor/etc/perf).
— Mishaal Rahman (@MishaalRahman) April 7, 2018
If we had to guess we would say that one is the Mi Note 4, since the mid-budget segment of Mi has always used the latest 600 Snapdragon series see Mi Note 3 SD660. The second phone is guessed to be Mi Max 3 as it is the other category that is powered by the same series of processors but a weaker one, the SD625.
The Qualcomm Snapdragon 670 is made using a 10nm manufacturing process. It is similar to the Snapdragon 660, it has an octa-core SoC not with 4+4 CPU core arrangement but with 2+6, that is with 6 power efficient cores ARM Cortex-A55 (Kryo 300 Silver) and two high-end cores ARM Cortex-A75 (Kryo 300 Gold). CPU cores have 32 KB of L1 cache and 128 KB of L2 cache for each cluster and 1024 KB of L3 cache for the full SoC. The Snapdragon 670 GPU is Qualcomm Adreno 615, which runs at 430 MHz to 650 MHz, with a dynamic boost clock of 700 Mhz. It support both UFS 2.1 and eMMC 5.1 flash memories. The chip features Qualcomm Snapdragon X2x modem, which is theoretically capable of pulling up to 1 Gbps speeds.