3dmark 11 scoring issue

[Nebthet]

Hello everyone,
my pc used to score P10.6k with the 280.26 drivers, on a 2500k @ 4.6ghz + 570 SLI @ default, never touched any setting for a month, and my score suddenly became P10.3k, with both physic and graphic score lower by about 300~400 pts.
One week ago I installed the new beta drivers and got to P10.8k so I was pretty happy, but today I tested again, no other settings changed again, and it won't get past P10.4K.
I know some random changes are natural, but 400 everytime? What could be the possible causes of this? Shall I start worrying?

[shoebox]

It could be a background program using up some CPU power, at-least that is what one of my friends said was happening to him when his score was changing.