You can mix RAM brands and speeds, but it gets complicated.

Yes, physically it will work. The motherboard will find a stable configuration, but that usually means both sticks run at the slower stick’s speed and timings. So if your old stick is 2400MHz and your new one is 3200MHz, both will run at 2400MHz. That’s not ideal, but it’s functional.

The bigger issue is stability. Different brands and even different batches of the same brand can have slightly different voltage requirements or timing profiles. You might get crashes, blue screens, or the system simply refusing to boot. If you’re lucky, it’ll be fine. If not, you’ll spend an afternoon swapping sticks and resetting BIOS.

If you’re building or upgrading a PC, buy a matched kit. It saves the headache. But if you already have one stick and just need to get more memory for cheap, mixing is worth a try. Just know you’re rolling the dice on performance and reliability.