Continuous loss of RAM

[chaoscreator]

i had to format the hard disk and use different computer's system back-up cd to get my machine to work. Later, I installed drivers for hardware from the cd supplied by my machine's manufacturer. Now i notice dramatic and continous loss of RAM; during last 12 hrs its capacity fell to a third and even when i close all programs it remains at steady half of it's capacity ( and later it falls again ).
The drivers' cd does not include a driver for system (MSI MS-6775) or processor. Is that the reason? If so, where can i find these drivers?

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