If you still have the documentation that came with your PSU, you can check the specifications listed in the manual or datasheet. This method is useful if you've lost the label on the PSU or can't access the PSU itself.
: Most modern cases use thumb-screws or standard Philips screws to hold the left-side panel in place. how to check psu wattage
He couldn’t read it without unscrewing the PSU and turning it around. But before doing that… If you still have the documentation that came