Your motherboard's manual tells you the max RAM per slot.

Check the manual or spec sheet for your exact motherboard model. That’s the only reliable source.

The per-slot limit is usually the same for all slots and is often determined by the CPU’s memory controller, not just the board. But older boards (DDR3 era especially) sometimes cap each slot at 8GB or 16GB even if the CPU supports more. If you’re installing one giant stick, you need to know that number.

Quickest way: search “[your motherboard model] specifications” on the manufacturer’s site. Look for “Maximum memory per slot” or “Memory type” details. On Windows, CPU-Z can show you the current slot configuration and SPD info, but it won’t tell you the limit. For that, you need the official specs.

If you can’t find the manual, try a forum like Tom’s Hardware or reddit with your exact model. Someone has probably already hit the limit.

Don’t guess. Buying a 32GB stick for a board that only takes 16GB per slot is a waste of money.