I'm building my first PC gradually and ultimately want 32GB of DDR5 using two 16GB sticks. Would it be reasonable to install one 16GB stick now so the system is usable, then buy a second stick later from the same retailer with the same brand, speed, and specifications? I'm wondering how much compatibility risk there is, especially with a Ryzen 7 9700X, B650M Gaming Plus WiFi motherboard, and Radeon RX 9060 XT. Would it be better to buy a matched 2x16GB kit from the start?
3 Answers
If your budget allows it, I’d buy the 32GB kit now. You’ll get dual-channel performance immediately and avoid the possibility of compatibility issues later. If you genuinely need to spread out the cost, one 16GB stick is a workable temporary solution—just treat the second stick as a potential compatibility gamble rather than a guaranteed upgrade.
It will work, and DDR5 is generally pretty forgiving. However, one stick runs in single-channel mode, so memory performance will be lower until you add the second module. Also, 16GB can be enough for some games, but it’s becoming a fairly tight amount for Windows, multitasking, and newer titles.
The main risk is that buying the same model later doesn’t guarantee the exact same memory chips or timings. Manufacturers can change the chips used under the same product SKU, and a mixed pair may not run reliably at the advertised EXPO/XMP settings. It might work perfectly, but you could need to lower the memory speed or disable the profile.

A matched 2x16GB kit is tested together, so it’s the safer option if you care about running the advertised memory profile without troubleshooting.