The most reliable way to find your wattage—especially if you didn’t build the PC yourself—is to look at the PSU itself.
Your graphics card isn't performing at its expected speeds because it isn't getting enough "juice." how to find power supply wattage
If you bought it online, your order history will usually list the exact PSU wattage under the "Specifications" tab. How Much Wattage Do You Actually Need? The most reliable way to find your wattage—especially