Any problems upgrading a Gateway PC?

So I've got a Gateway PC that I wouldn't mind upgrading, but the last one I upgraded had some weird problems happen after I upgraded the PSU and GPU. Anyway, I was wondering if anyone else has had any problems. I was thinking of upgrading my RAM, PSU and GPU. 


CPU: AMD A10-5700 3.4GHz

Mobo: Some Acer piece of crap

RAM: 400 MHz piece of crap DDR3, 8GB

GPU: AMD 7670 HD Discrete crap

HDD: 1TB something


That's the rig. Should I just scrap it and build a new PC inside the case, or upgrade it? The system name is a DX4380. I was thinking of getting either an HD 7850 or an R7 260X, maybe a 270X. 

Let me know, give me some ideas and feedback, or just tell me "Screw it, get a new PC!" 

Screw it, get a new PC!

get a bigger psu and this

If you're going to get the ram, psu, and gpu, you'd be better off just getting the rest of the parts needed to build a new pc.