I have a XPS 702x 3D laptop and i want to upgrade the memory. It currently has the stock memory

DDR3 PC3-10600

Using newegg.com's memory upgrade tool, it recommended

CORSAIR Vengeance DDR3 PC3 12800

since the PC***** is different are they compatible?

if they are

Can i mix 4GB of default and 4GB of this?

thanks so much

---Lahiru