HTC has posted a teaser image with the number 820 written on it, leading us to believe the phone in question is the Desire 820. The image was posted on the company's Weibo account, which is a strong indication of its launch in China.
However, there's also IFA 2014 just around the corner and HTC may very well announce the Desire 820 in Berlin. There's very little information regarding the phone's specifications and launch date.
There's information floating around that the Desire 820 will feature a Qualcomm's Snapdragon 615 SoC packing a 64-bit octa-core CPU (four 1.8 GHz Cortex-A53 cores and four 1.0 GHz Cortex-A53 cores) and Adreno 405 GPU.
Sadly, at this point, all we have is the teaser image above and the aforementioned rumor. We'll have to wait until IFA to know more about the Desire 820, if HTC decides to unveil it then.