What causes this RAM or any other thing?

I recently upgraded my system from Dual Core to Core i3 including motherboard and ram etc except my XFX HD 4650, now the graphics appears choppy and lines like teeth's were appearing on the objects please check the link. a href="http://imageshack.us/photo/my-images/854/capturenvn.png/" rel="nofollow"http://imageshack.us/photo/my-images/854…/a These same lines are appearing around the buildings and other objects too while movement, in case I replaced my HD 4650 with your XFX HD 5570 GDDR3 1GB and problem didn`t resolve, now whenever I watch video online then I face "Display Hardware Error" atikmdag stopped responding and successfully recovered, this also happens while playing game on XFX HD 4650 but now on HD 5570 this only happens while watching online video, a adobe flash player opens and then on the lower right corner of the screen warning appears containing this error, and when I return on my desktop then a href="http://imageshack.us/photo/my-images/846/capturejn.jpg/" rel="nofollow"http://imageshack.us/photo/my-images/846…/a There are no driver problems or any other and yes when I run simple MemTest I get 20 error in one RAM stick and 12 errors in other RAM stick, and my ASUS-P7H55-M LX requires kingston Qimonda and I use Kingston Harvest can this cause problem, and yes can System memory(RAM) cause problem in display and my GPU is OK because I replaced it few days back. My system specifications :- Corei3 540@3.06 GHz 4.00 G RAM DDR3@1333MHz ASUS P7H55-M LX Motherboard XFX RADEON HD 5570 1G GDDR5 650M 450W PSU 750 SATA II Thanks.