FPS fluctuate too much

[Vioras]

I recently bought a gtx 670 card, when I played games with it I noticed that it's not an improvement, it's only worse over my old gtx 560. In several games my fps fluctuate, for example in BF3 sometimes im at 50 but then im at 15 and so on. What I also notice is that I got choppy gameplay even when I have 50-60 fps, it doesn't look like im playing at 50 fps but at 20. I hope someone knows the problem.
System specs:
Mainboard : MSI IONA
Chipset : Intel H57
Processor : Intel Core i5 650 @ 3200 MHz
Physical Memory : 6144 MB (3 x 2048 DDR3-SDRAM )
Video Card : NVIDIA GeForce GTX 670
Hard Disk : Western Digital WD1001FAES-60Z2A0 (1000GB)
DVD-Rom Drive : FQHMLW FWHY3OLMV
DVD-Rom Drive : Hewlett-Packard DVD-RAM GH40L
Monitor Type : LG Electronics E2281 - 22 inches
Network Card : Realtek Semiconductor RTL8168/8111 PCIe Gigabit Ethernet Adapter
Operating System : Windows 7 Home Premium Home Edition Media Center 6.01.7601 Service Pack 1 (64-bit)
DirectX : Version 11.00
Windows Performance Index : 5.9 on 7.9

 

[HEXiT]

why 3 sticks of ram. h57 and i5's only allow dual channel and if its faster than 1333 you will be forcing it into single channel mode only...
remove 1 stick and if you can set the ram to 1333 manually. (make sure you use the rams jdec values.
for instance mine is ddr3 1600 8-8-8-25 but it has a jdec that allows me to run it at 1333 7-7-7-19 @1.5v(use cpu-z to see what jdecs your ram supports) using it this way the ram is actually more efficent and allows me to use all the ram slots instead of being limited to 1 ram stick per channel.
your also running a budget cpu with a high end gfx card. which isnt a good idea. it will work well with games like cod4 and starcraft 2 but will bottleneck badly on games like bf3.
swap your old gfx back in for now until you can afford a better cpu and a better motherboard perferably a p55 or z77 along with a 2500k or 3570k or similar...

as it stands your system is completely unbalanced and because of this your not gonna get the performance you have payed for on the gpu.

ps. when you ask a question make sure you select the right category in the ask the community tab. there are 3 options, poll, question, discussion. if you select anything other than question you wont be able to reward the best answer. you can however ask a mod to make the topic a question as and when you get the best answer