You get 65fps at 2560x1600 in Crysis? May I ask where you took the reading? Not in the shipyard area I suspect, that takes a royal dump on the CPU and will surely ruin my 60fps plans for Crysis once I get my 'sufficient' GPU.
I've built a custom benchmark in the ice/alien area. It's far more demanding than the harbour area, or anywhere else in the game for that matter.
I also run custom game settings as maximum levels would slideshow even a Titan.
I suppose at 60Hz old UT2004's CPU dependency probably doesn't cause you any grief, but I fear I won't be having 120fps onslaught matches until 2020 at this rate. I apply the same logic as you when it comes to overclocking, but sometimes I think I should get another 2600k and overclock it with two cores disabled just for that damned game. Unreal II is a menace too, what with it's dynamic shadows. Everything was going great until I touched those sliders.
You can't have had many bots going in the UT test, that's another member of the cripple thread brigade. IIRC last time I tried it on the 2600k, 20 bots in facing worlds already destroyed my 120fps target. Not that the engine can tolerate 120fps without glitching anyway...
I just tried Facing Worlds in UT99 with 16 bots (game maximum) and it ran at a constant 120 FPS.
In UT2004 I loaded 20 bots and it never dropped below 90 FPS, which is perfectly fine given the map recommendation is 6-12 players. Sure, you could load even more bots, but that just becomes a synthetic CPU test.
As for Unreal 2, I use maximum shadow levels (except blur which I don't like because it makes the shadows harder to see), and the game mostly runs at a constant 120FPS at my settings. My stress area benchmark is the worst-case framerate I ever see.
EDIT: I have another question. I'm using 306.23 drivers on the 580, and every time I try a newer driver I end up rolling back because F.E.A.R (among others) start exhibiting some strange behavior. I can see the fraps jumping a frame above/below my V-Sync cap and feel hitching. When I get my Titan or GTX 780/s, a driver update will be inevitable. Did you notice any hitching of any sort in FEAR with the new drivers?
I don't use vsync so I can't comment there, but the Fear 1 works and looks great @ 4xSSAA on my system.