There's no reason to cross-post; just about everybody visits both boards. And I don't think your E8400 is to blame, either.
You should be able to reduce the stuttering if you turn on V-sync (triple buffering). I was also able to minimize stuttering by setting a framerate cap. I suggest you do the same: gfx_maxfps 35 (or whatever value you want).
And if you just do a google search, you'll see people with very different rigs (Radeon vs. Geforce, dual vs. quad core processors) experiencing micro-stuttering in the game.