If i go with the GTX 970, would i have to upgrade it again in the future? I don't plan to play on 4K or 1440, i just want to play on 1080. So would GTX 970 be the best answer?
And...yeah, looks like i have a crap PSU.
I play games at 1080p, i play GTA V, and COD : AW. And the framerates is so low. My brother build this PC for me in 2012 if i'm not mistaken, it costs about 100$ back then.
My target framerate is 50 and above at High/Very High setting in GTA V and AW.
Thanks for answering!
Your CPU is quite strong for gaming even without an overclock. You're being held back massively by your GPU, which is very weak. The R9 390 is probably the best reasonable 1080p gaming card. The GTX 970 is right behind it. The R9 290x is probably a little better than a GTX 970, the R9 290 a little worse.
No matter which GPU you choose, I would update that power supply. A four year old 450W noname unit will not power an R9 290/290x/390 and probably wouldn't be too good with even a GTX 970 either. There are some nice 80+ Bronze power supplies that are often for sale for great prices. XFX makes very good 550W and 650W units. I'd get the 550W if you go GTX 970 or the 650W for R9 290/290x/390. The Antec High Current Gamer power supplies are pretty good also. For GTX 970 I'd go with a 520W unit, for R9 290/290x/390 I think their 620W would be good too. You can often get these power supplies for $50-$60 after rebate.
Try to get to 8GB or more of RAM if you can too. RAM is really cheap right now and GTA V can use 5-6GB by itself if you're playing it for a couple of hours or more (there must be a memory leak in it). Also, what case do you have? Having good airflow matters more with an R9 290/290x/390 since they use more power. You don't need anything fancy though, as long as you have a clear path for air to be taken in through the front of the case via say a 120mm or 140mm fan, you have a bottom mount for your power supply, and back and top 120mm fans or better that's plenty to cool pretty much any single GPU. Most budget cases will satisfy those requirements nowadays.
If your case doesn't have good airflow at all you might be best off with a blower style GTX 970. By blower style I mean these kind of cards, where the fan is an intake fan and there is a shroud to direct heat out the back and out of the case. A blower card is good to go with if your case's cooling is really bad, since it doesn't put heat into the case. But they run louder and hotter, and thus don't boost as highly as the open air cards more appropriate to a case with reasonable airflow.
The R9 290 and R9 290x have horrible blower style coolers that can be really loud, and they were such disasters that they never even released blower R9 390. But if you have reasonable airflow you're much better off with the kind of video card that exhausts heat into the case, to be carried away by the channel of air flowing from front to back in the case. The GPU will run cooler, and thus faster, as well as quieter. Something like these kind of cards with an open design.
If you have any kind of reasonable airflow case I'd probably grab a 620W-650W power supply and an R9 390 (MSI Gaming and Sapphire Nitro are really nice). To save a couple of bucks you could grab a GTX 970 (look for Gigabyte G1 Gaming, MSI Gaming, or EVGA SSC [not SC though]) and a 500W or so power supply. If you dig around you might find the R9 290 and R9 290x on sale for incredible prices, though those deals are mostly dried up by now sadly. The PowerColor PCS+, Sapphire Tri-X, and Sapphire Vapor-X are really nice here. Use the same PSU you'd use for a 390 with a 290/290x, as the 290 and 390 are pretty much the same GPU except the 390 comes with faster memory and more memory (though the 8GB of a 390 isn't much use over the 4GB of a 290/290x for 1080p). I'd stay the hell away from Asus R9 290/290x/390 though. Their cooler on the 290/290x was awful and I wouldn't give them the benefit of the doubt on the 300 series either.