Valve loves to warn people about about the risks of do-it-yourself Steam Deck maintenance, and that now extends to upgrading the storage. In a response to a PC Gamerarticle on modding the Steam Deck, Valve hardware designer Lawrence Yang warned against upgrading the device’s NVMe SSD. While it’s technically possible, the M.2 2242 drives (22mm wide by 42mm long) you frequently find in stores are hotter and more power-hungry than the 2230 models (22mm x 30mm) the handheld was meant to support. You could “significantly shorten” the longevity of the system, Yang said, adding that you shouldn’t move thermal pads.

The PC Gamer story referenced modder Belly Jelly’s discovery (initially reported by Hot Hardware) that it was possible to fit an M.2 2242 SSD in the Steam Deck, albeit with some design sacrifices. There were already concerns this might lead to overheating problems. Yang just explained why it’s a bad idea, and outlined the likely long-term consequences.

The alert might be a letdown if you feel limited by Valve’s maximum 512GB storage and don’t think a microSD card (typically much slower than an SSD) is an adequate substitute. With that said, it’s not shocking — mobile devices like this often have size and thermal constraints that make it impractical to upgrade at least some components.