Yesterday my computer automatically shut down, then cannot switch on anymore, before I changed my PSU no light no function at all, after I changed my PSU the switch on button got light, and the fans spin for 0.5second then totally stop there, so asking maybe the problem on PSU, motherboard or both?

Another question, my spec
Intel g4400 processor
Gtx1050
Motherboard (forgot)
PSU 550W
HDD 750
SDD 250

Asking it is worth to upgrade my processor to i5? Have the thoughts about upgrade current PC processor, or save money to buy higher spec pc

if you know the model of your motherboard, then you can check which processor your motherboard can support

but i would recommend change motherboard, processor and ram together, because that processor is the bottleneck for that graphic card GTX1050