Best Upgrade option?

[Socaddict]

So, my current pc does its job well enough, but its sometimes struggling with some more recent games at my monitors resolution - 1440p. I'm looking to spend between £100 to £150 to get the best bang for my buck in terms of upgrade potential, the only problem is that anything has to fit into my sugo SG05 case.

Current spec:
i5 2500k
ASRock Z68M-ITX/HT
8GB DDR3 1333MHz (2*4GB)
GTX 660ti OC
Sugo SG-05 with the 450W PSU
Crucial M500 240GB SSD as boot and gaming drive

Options I'm considering:
second hand gpu, maybe a 290 if I cut out the front part of my case
16GB RAM (2*8GB - there's only 2 RAM slots on the mobo)
~400GB SSD to replace boot drive

I'm mostly looking at the GPU upgrade, but what would my best option be?

Thanks!

 

[stulid]

Add a new GPU and overclock the CPU.

Your PSU will limit you I think to GTX960/970.

8GB of RAM is fine for gaming.

Do you have an aftermarket heatsink?

Check your motherboards BIOS is upto date.

 

[Socaddict]

Got a scythe shuriken rev B low profile on the CPU. I was thinking about looking into a AIO watercooler for it though. how big a step up is the 960 over the 660ti?

I've read plenty of people running 290s with the silverstone 450W that I have in it. hence thinking about one of those, as I've seen them go for £120 to £140 in the MM.

 

[stulid]

The 960 is double a 660ti.