M17x r4 upgrade to GTX 880
I have a M17x R4 currently running the Radeon 7970m. I am interested in upgrading to the GTX 880m 8gb. Does anyone know if the 7970m heat sync will work with the 880m? If not can you get the correct heatsync through dell? Is it possible to purchase the GTX880m through Dell? Thank you for your unputs.