Yes, it is possible. Having a lower power PSU than your fully-loaded PC can potentially consume may damage a different component or itself. For example, if you have a 500W PSU, while the PC could potentially consume 550W or 600W. Then you won’t notice anything probably. That’s because, normally your PSU does not max out, but the potential is there. It is never recommended and you should change the PSU to a higher capacity PSU as soon as possible. Having a small headroom is always better. You can overclock and it also gives the GPU to stretch and provide the best performance.