Graphics card is causing system freezes, Time to RMA??

[fullHDgamer500]

My rig is this
CPU..Intel core i5 2500k @3.3Ghz
Motherboard..Asus P8P67 REV3.1
GPU..Sapphire HD7850 OC edition
PSU.. Coolermaster GX750W
RAM..8GB Corsair Vengeance 1600mhz
Case.. Antec 900 V2
HDD..2x1TB WD Caviar green
Monitor .. 24" AOC Full HD@1920x1080

The problem is with my graphics card,I bought it 3months ago.At first it ran fine and last week while i was surfing web it caused system freeze with annoying colourful dots and lines all over the screen.The only option was a hard restart.
After hard restart my windows wont load.Log on screen wont display and after that starting windows the screen became black with no response. It only ran i safe mode with a lot a loot of dots ,vertical and horizontal lines over the screen and at resolution of 800x600.
I reinstalled my windows and everything was fine again.I installed the latest drivers 12.11beta and it ran fine for 2 days after which once again i was playing BF3,it froze and i had to reinstall windows.Now it have happened 4 to 5 times that it causes freeze while playing bf3.
For making sure it was not BF3's fault i ran Furmark stress test for 30minutes and it froze after running 25 mins.
I switched back to 12.10 drivers and the problem not gone,
I ran memtest for 45 mins but all fine and no error,
My temps are either not bad.Idle is 28 or 30*C and under full load ( running furmark) it never goes above 64*C.
My PSU is also sufficient.It requires only 500w PSU recommended but i have a 750W PSU.
I have not overclocked my GPU yet and it is factory OCed at 920/1250 .
I have now switched back my old Nvidia GT440 and it never causes freeze.It ran furmark for 40 mins with temps reaching upto 96*C but never freezes.

I think following info is sufficient,so please tell should i return it to the shop from where i bought it , It still holds warranty of like 7 months...
I am very much worried so please help me

 

[Bellular]

If I were in your position I would return it. Sounds like you got a damaged / problematic card. A replacment card would definatly cut down on the stress and hassle and seems to be the safest option. Hope it goes well for you!

 

[fullHDgamer500]

Thanks for your quick reply!
I am going to return it,
It worked fine for me during first two months,never had a problem with it.I played and ended Metro 2033 , NFS:The run and other GPU intensive games on it without any problem but mainly it started causing problems when i first played BF3 for continuous 3 hours ,It caused freeze(previously i played Metro 2033 etc games for maximum 1 or 2 continuous hours).