A:Answer Hello and thank you for your question. This Desktop has a total of 3 M.2 slots. One is an M.2 socket 1, key A, type 2230 for WLAN use, and the other 2 are M.2 socket 3, key M, type 2280 for SSDs (PCIe Gen 4.0 x4). One of those M.2 socket 3's is currently in use with the existing 512GB SSD, and the other is available to be upgraded. While it is possible to upgrade the storage on this Desktop yourself, we recommend that upgrades be performed by the IT professionals at Best Buy's Geek Squad to avoid installation complications.