I upgraded from a 5750 to a 7870 a couple of days ago and honestly i'm not that impressed. I do not actually see any improvement in BF3. At first I though it has to be drivers and then I read into that. I find out that people were experiencing a similar problem with their drivers so I downgraded to 12.6 like much of them had done. I didn't get to much of an improvement from doing that so I then thought that there is a slight chance it could be a defective card. But After powering up PS2 I notice almost double the frames I used to get so I took my attention away from a faulty card. I haven't ran any benchmarks to see if the card is placing where is should be but atm it really feels like I still have my 5750 in my case.
In BF3 I get an average of about 40 fps on preset high at 1400x900. According to reviews and benchmarks of this card I would expect that fps with ultra settings at 1080p.
In Msi afterburner the gpu load doesn't go above 60% and when I have task manager open my cpu is around 90%. This is leading me to think the processor I have is bottle-necking it.
When I first got the card I thought the card may of been defective but from what i've read It may be the cpu. The being defective still isn't out of the question.