Most cost effective upgrade:GPU, CPU, mo-bo, RAM?

tredbor89

Honorable
Dec 29, 2013
1
0
10,510
Hello everybody,

Been a long time visitor to the site and usually try to solve any problems i have via my own researching. However I am at a loss as to what PC component to upgrade next. I play a very mixed bag of games (from FPS's (BF4), strategy(Rome 2) and various racing and adventure games). Currently i have BF4 with every setting on low or off at a res of 1440x900, running between 5(explosions lots of action etc) to mid 20 fps.
I've read a lot about CPU's and GPU's and bottleneck related problems and so am cautious about which piece needs to be upgraded first. I have about £90-£130(max unless its some unbelievable part at a miraculous price). My initial thoughts were a GPU at about the Nvidia 650Ti level or some quad core CPU. Ideally I'd like to play BF4 at the 'medium' settings with 25+ fps. My question to you is:
What would be the most cost effective upgrade?
I have copied Speccy's report on my system components.

Windows 8.1 Pro 64-bit
CPU
Intel Pentium G620 @ 2.60GHz 35 °C
Sandy Bridge 32nm Technology
RAM
4.00GB Dual-Channel DDR3 @ 532MHz (7-7-7-20)
Motherboard
ASRock H61M-VS (CPUSocket) 27 °C
Graphics
L226W (1680x1050@60Hz)
1023MB NVIDIA GeForce GTS 450 (PNY) 37 °C

Many thanks for any help.
Regards,
Rob