I feel dumb now, anyone reading this, please don't give me a hard time, I am posting this to help others with this issue... 550TI User
-If you aren't sure what overclocking or underclocking Is you probably shouldn't mess with it. -If you don't know what you are doing you can DESTROY your system or graphics card.
-I am in no way shape or form responsible for damage to anyone's machine or card.
Like many others I bought a brand new machine and G.Card just for D3. I had stutter issues since the may patch. Before the patch I could play stutter free for hours. I tried everything I could find on this issue to no avail... I recently started digging deeper into overclocking and underclocking to improve D3. I downloaded MSI afterburner only to find out my card was still set at stock values (Witch is normal, I know) My core clock was set at 900.
Something I also noticed... Random system spikes on my machine. Then it came to me... My graphics card was severely underclocked for my system causing bottlenecking. I then went into MSI overclocked to 1000 after a few before and after tests and now after months of stuttering D3 runs perfectly. Of course I'm sure I won't be able to keep it this high for other games, most high end games run my G.Card GPU to almost 100% usage. Here's the kicker, Diablo 3 only uses half of my cards GPU usage therefore I can raise my core clock to a comfortable level along with a balanced voltage and fan settings.
I feel so dumb, I was trying all these other fixes when the real problem was right under my nose. I am also VERY sorry for blaming Blizzard for this issue.