Crysis
Rather than test a range in resolutions in Crysis, we tried several different settings, all using the game's "high" image quality options. Crysis has another set of "very high" quality options, but those pretty much bog down any GPU combination we've yet thrown at it. In fact, "high" is pretty demanding, so we've scaled back the resolution some, too. We tested performance using the benchmark script Crytek supplies with the game.

Also, the results you see below for the Radeons come from a newer graphics driver, version 8.451-2-080123a, than the ones we used for the rest of our tests. This newer driver improved Crysis performance noticeably over the older one, both in benchmarks and when playing the game.

The X2 tops all single-card solutions at 1680x1050, but it's not quite as quick as the Ultra at 1280x800 with 4X AA (nor is anything else). Interestingly enough, this is one application where the Radeon HD 3870 CrossFire config's superior memory bandwidth seems to give it an edge over the X2.

Unreal Tournament 3
We tested UT3 by playing a deathmatch against some bots and recording frame rates during 60-second gameplay sessions using FRAPS. This method has the advantage of duplicating real gameplay, but it comes at the expense of precise repeatability. We believe five sample sessions are sufficient to get reasonably consistent and trustworthy results. In addition to average frame rates, we've included the low frames rates, because those tend to reflect the user experience in performance-critical situations. In order to diminish the effect of outliers, we've reported the median of the five low frame rates we encountered.

Because UT3 doesn't support multisampled antialiasing, we tested without AA. Instead, we just cranked up the resolution to 2560x1600 and turned up the game's quality sliders to the max. I also disabled the game's frame rate cap before testing.

Here, the X2 produces a higher average frame rate than the Ultra, but its median low frame rate is almost the same. Amazingly enough, nearly all of these cards can run UT3 acceptably at this crazy resolution. Bottom line: UT3 performance shouldn't be a problem for you with the X2.