First of all, you'd be a "noob" if you dropped $600 on some overpriced flagship card as opposed to getting similar performance for cheaper by running crossfire (which a true noob wouldn't even know was possible).
Other will pipe in with their experiences but I really don't understand why some people get such horrid microstuttering and I can't say I ever noticed such a thing with 4850 then 6850 crossfire. Though that may not actually be your true issue.
What resolution is that 27" and what are your graphics settings? You may very well be running out of VRAM with just 1GB. Would not cause "microstutter" but definitely low fps and overall sluggish feeling.
At 1200P with 4X MSAA and Ultra except shadows I use damn near my whole 1530MB. Note MSAA uses a lot of memory and also affects performance pretty horridly on AMD cards, unfortunately.
“i dont care what consoles have they dont have mouse and keyboard” -crazyeyesreaper