There is no doubt about it, the hottest news coming from the Game Developer Conference are what game developers think of Kepler, i.e. GK104 and GK107 chips. The GK104 will take shape as the GTX 680.
According to the stories coming from CeBIT 2012 show in Hannover, Germany – Kepler is just weeks away. The first desktop part being launched is known under the codename GK104, and in the old product naming convention, the card would be named GTX 660 Ti or maybe GTX 670 Ti.
If rumors are true, NVIDIA sees this part as a competitor to Radeon HD 7950 and 7970 and decided to give the new Kepler the top end name – GeForce GTX 680.
GeForce GTX 680 is featuring 1536 CUDA Cores divided into 96 SM cluster, a 256-bit memory controller connecting to 2GB of GDDR5 memory. Graphic card vendors will also offer a variant with 4GB of GDDR5 memory, and according to the sources – for the first time since GDDR5 was introduced, a NVIDIA GPU is able to drive clock the GDDR5 memory higher than AMD, which created the memory standard.
There was a lot of confusion about the hot clocks, i.e. their disappearance an re-appearance. The stories we were told cite that the company adopted a CPU like approach to its upcoming GPU: dynamic clocking.
Dynamic Clock Adjustment is very similar to former “hot clocks”, with the difference that GK104 comes with several dozen power planes, and will operate on varying clocks depending on the computational load, card temperature and the power consumption. As we posted several days ago, the complete GK104 chip will operate at a lower clock, very similar figure to GTX 480: low power mode is 300 MHz, standard is 705 MHz extendable to 950 MHz – while the cores alone will be able to reach 1411 MHz when the chip is loaded to 100%.
The 2GHz QDR clock (six gigahertz effective) should be good enough for massive 192GB/s, i.e. significantly less than 7950 and 7970, but significantly higher than 7850 and 7870.
The rumored performance is a mixed bag between HD 7870 and HD 7970: 10% faster than Radeon HD 7970 in Battlefield 3, but 10% slower in 3DMark11. Also, Epic's Samaritan demo, which required three GTX 580 boards only requires a single Kepler, i.e. a single GK104 chip.
When it comes to availability, partners are typically saying one thing in public, and another thing behind closed doors. The availability isn’t known, and it won’t be known until partners receive launch quantities. The estimations we heard went from pessimistic “small quantities of Kepler graphics cards only”, “no overclocking boards at launch” to “they had the first silicon in September 2011, they (NVIDIA) must have to stacked up the chips to flood the market and claw the market and mindshare back”.
As usuall, the rumors need to be taken with a few grams of salt (the Hawaiian one being one of most tastiest salts I have ever tried).