A:Answer Contact your local Geek Squad for more information, you can set up an appointment right on the website or the app as you WILL need an appointment to check the device in and walk ups are usually frowned upon (and put strain on the staff). Assuming there's nothing unusual about your case that would cause complications, they would most likely have no issue removing the previous cards and installing a new 3070. Your system should most likely be able to support it, but keep in mind there may be other parts that need to be upgraded to utilize the 3070 and you may need to order replacement PCI slot covers (where the cables plug in) unless your okay with an open hole where the second graphics card was.
Tech Support or Total Tech Support should cover the labor for in store services, but additional fees may apply if you would like them to come to your home. You will need to pay for any parts (including the 3070). Once again, please schedule an appointment ahead or contact your Geek Squad closer to release to see what availability they have for walk ins or you may be turned away if you show up without an appointment and they simply do not have the staff on hand to take you along with scheduled appointments.