Looks like online retailers are going on a spree by listing several reference GTX 670 models online, The latest is PcCanada who have listed the Gigabyte GTX 670 for $415 featuring a core clock of 980MHz.
The card features a stock core clock of 980MHz which suggests this could be a factory overclocked variant sine the reference clock frequency is somewhere around 900-950MHz. This also shows that the Boost frequency would be well over 1GHz range though we don't know the exact specifications.
Other details show that the card features a 256-bit 2GB memory, is DX11 compliant and features compatibility with PCI-e Gen 3. Display outputs include DVI-I, DVI-D, HDMI, Display Port. Cards official retail price would be set at $399 and would be available around the first week of May with announcement imminent today in Shanghai, China.