System Unbalanced and Bottlenecked

hey all I have recently updated my rig however its less than holding up expectations despite the price tag on my GPU ($400).
My question is what I will need to do to my PC to get a much more stable FPS in games and over all stable and balanced system, or an answer to why my system seems to be folding under the pressure of games such as Witcher 2 which my FPS ranges from 40-20.

My System Specs are:

ASROCK H71M-DGS

Intel Core i5 2400 3.1 GHz

4GB RAM

AMD Radeon 280X

Corsair 550 W PSU


Could my problem be caused by my lack of RAM as I need to find my other stick I have lost it somewhere.

Or is it simply an out-dated CPU?

Or could it be something else?

Well I dont know if this is a better indicator than a game but Running Furmark at a GPU Usage of %99 and Temps of 75 degrees the card was running an average of 25 FPS

Something else I want to add to this thread is an issue that I has buggun happening where my screen simply goes white I can hear all sounds and everything appears to be fine however there is no display apart from a white screen forcing me to manually shut of the computer using the power button, it seems quite clear to me that this problem must link up to my FPS drops and over all GPU stability and performance telling me that theres definitely either some really bad drivers or my hardware is suffering some sort of voltage issue or something along the lines of that However apart from a very small reservoir of experience built on personal troubleshooting I really don't have any idea what im talking about and all help is greatly appreciated!

am desperate for awnsers jimpz help a brother out!

Its a corsair as I previously stated yes there are no reminents of the previous drivers as the HDD was formated and a fresh copy of windows was installed I know its borderline however I was assured by a Tech Guy (who did not work at the store in which i bought my GPU) that the integredy of the brand would match up better than a more disreputible brand with a some what fake representation of Wattage simply branded on the front it replaced a GTX 560 however its a brand new PSU aswell The only spare parts I have to test anything out with is my original 650 W PSU and as for the driver package is im not to sure I simply fill out a few things on the AMD website and downloaded something called catalyst Software Suite.

its 14.100.0.0