Star Citizen will require an AVX compatible processor to run the game, starting with the Alpha 3.11 update. This means that any CPU that doesn’t include AVX instruction support won’t be able to run the game. Although most consumer CPUs since Intel’s Sandy Bridge (2nd Gen) and AMD’s Bulldozer support basic 128-bit AVX instructions, a lot of lower-end parts such as the Celeron and Pentium lineups don’t.

As a result, Star Citizen will cease to function on these parts (including the latest 10th Gen variants) as the latest patch is rolled out. Although many will criticize this step, we don’t believe that it will be an issue for the majority of players as AVX has long been a part of mainstream processors, and should help upgrade the game engine for modern hardware.
Although AMD’s Athlon lineup supports AVX, it’s notably slower than on the higher-end chips. So much so that even SSE2 instructions run faster than AVX on these parts. Regardless, this means that they will support the game, unlike Intel’s entry-level products.