Spotted back in June on a mysterious Asus Zenfone, The Qualcomm Snapdragon 821 SoC is now official. The Snapdragon 821 SoC is built upon the widely popular Snapdragon 820 SoC. Qualcomm also confirms that the new SoC will offer 10% extra performance over the Snapdragon 820. It is again using a quad-core Kryo CPU with speed on the big cores now reaching up to 2.4GHz, which are limited to 2.2GHz on the current gen Snapdragon 820. Qualcomm has also confirmed that the phones powered by the Qualcomm Snapdragon 821 SoCs will be available from the second half of this year.
Besides this, Qualcomm hasn't released much information about the new SoC. Rumours suggest that the Snapdragon 821 will feature the same Adreno 530 GPU as well. However, it is not yet clear if it will be clocked at the same 624MHz or a little higher. The rest of the specifications, such as the X12 modem, which can support download speeds of up to 600Mbps are likely to remain the same.
Coming back to the quad-core CPU cluster, although Qualcomm has confirmed that the big core will be clocked at 2.4GHz, the company hasn't said anything about the LITTLE cores. Rumors suggest that Qualcomm might raise the clock speeds from the standard 1.6GHz used on the Snapdragon 820 to 1.8GHz or 2.0GHz.
All that said, these are just speculations at the moment and will be official only once the rest of the specifications of the Qualcomm Snapdragon 821 gets announced.