If you cannot open the case, you can find the wattage through your records: How to Check Your PC Power Supply Wattage？ - GAMEMAX
If you are looking at the physical label (Method 1), you might see a lot of confusing numbers. To ensure you aren't looking at a low-quality unit masquerading as a high-wattage one, look at the . how do i check my power supply wattage
There is no software that can magically read the total capacity of a power supply. However, some software can detect the specific model name of the PSU if it communicates with the motherboard via data cables. If you cannot open the case, you can
The most reliable method is to look at the sticker on the power supply itself. If you cannot open the case