to which GPU can/should i upgrade? (gtx 650,i5)

[rontsip2]

my current (3 y/o) PC:
Operating System: Windows 7 Enterprise 64-bit
System Manufacturer: Hewlett-Packard
System Model: HP Compaq Pro 6300 MT
Processor: Intel(R) Core(TM) i5-3470 CPU @ 3.20GHz (4 CPUs)
GPU: NVIDIA GeForce GTX 650
Memory: 8192MB RAM
PSU: HP DPS-320NB-1A 320W
Screen: 1920x1080 60Hz
Usual FPS On LOW Setting (no V-sync): 50+
Games I Will Be Playing In The Future: BF4, GTA V, Fallout 4.
last year i started noticing that my pc is getting weak and every game i buy, i have to lower the settings (usually to the lowest) to be able to play normally.
what should i upgrade? most sites say my GPU is the problem.
my TOTAL upgrading budget is $320.
to which GPU can/should i upgrade?
thanks in advance.

 

[stavrosmast]

Tell us your budget, resolution,fps,game that you will be playing and your PSU model

 

[Dustybin]

The only spec I could find says the system comes with a 320w PSU. If that is the case you would need to budget for replacing that.

 

[Suzuki@1473780084@1473780163]

In a lot of prebuilt PC's you can't remove the PSU. Make sure this isn't the case before proceeding.

 

[Dustybin]

The spare part specs say it is an ATX form factor but yes you should investigate if replacing it is even possible. If you can't change the PSU you'll probably be stuck, even the 950 recommends more a 380w PSU.

 

[rontsip2]

In a lot of prebuilt PC's you can't remove the PSU. Make sure this isn't the case before proceeding.

how do i check if it's removable?

 

[Suzuki@1473780084@1473780163]

You look at how its mounted. If nothing is pusing against the case of the PSU, chances are its removable. You also want to look at the exhast fan of it. Chances are that's custom as well, meaning you would choke a different PSU.

 

[dustybin8]

There is a guide to replacing the PSU in this model but it looks like it uses a proprietary connector in place of a standard 24pin. The PSU looks easy enough to take out at least.