According to VideoCardz, NVIDIA will officially announce the GeForce GTX 880 at some point in mid-September. NVIDIA will be planning a big event for all major press around the world. Expect to see a Maxwell presentation, new hardware and of course Jen-Hsun telling you to buy that new SHIELD Tablet. The event will likely be live-streamed. The event will only be a paper launch for the GTX 880, expect it to show up in the channel a couple of weeks later.
The GeForce GTX 880 has recently been sent to a certification office. Graphics Cards are sent for validation at the very end of the development process. Normally this means that the card is ready and it is only a matter of weeks before it is available. This does not mean that AIB partners have their cards ready, it only means that the reference board has been validated. PG401 is the reference board for GM204-400, or the GeForce GTX 880.
It has been confirmed that the GTX 880 will have a 256b interface. It is likely that the reference models will ship with 4 GB of GDDR5 memory, but based on what we have seen from leaked images there will also be 8 GB versions as well. It is still unknown how many CUDA cores the card will have. The card in fact is very similar to the GTX 770 from a manufactures perspective. While the card is the successor to the GTX 780 it has more similarities to the GTX 770. The GM204 is basically a GK104 replacement, but that does not mean it will be slower than GK110 cards.
While the GeForce GTX 880 might not be the fastest card out there, it will not hurt your wallet that much. The expected MSRP is said to be between $400-$450 and it is not likely the card will be over $500.
We will let you know the most up to date information on the GeForce GTX 880 as soon as we receive it!