So i have an old optiplex 390 which is:

i5 2400 

4 gb ram 

And the same psu and motherboard of the optiplex 390, motherboard is 0M5DCD and am not sure about it. My question is can i put a gpu like gtx 1650 ? Because i saw many people on YouTube using the same pc i have and they used this gtx 1650 and it works good ? Some vids used gtx 1050ti, and if they works do i need to change the power supply? And what about ram can i have 16 gb ram ?

Note: Mine is the big case one