Low performance with r9

[InsertCoin]

I bought r9 270x and the performance is much worse than in internet benchmarks. I've got latest drivers installed from AMD site, I wasn't able to use Club3d ones cause i got no disc station at the moment. Rest of my spec is i5 2310, silentiumpc vero l1, 2x4gb 1333 MHz ram. Any suggestions what causes the issue?
Can it be software? I had Windows defender disabled for some time, avg was working tho.(should I reinstall Windows?)
I got around 7.5k points in 3d mark 11-that's one missing, 80 FPS in BF3 high, should be 100 with ultra settings.
Sorry for my bad english.

 

[InsertCoin]

Bump

 

[Vic 40]

I don't see what's wrong.Maybe you expect too much?