Core i5, Core i7, CrossFire, And SLI: Gaming Paradise, Redux?


Here’s the real deal: we can turn the settings down below 1680x1050 and show you 200+ frame per second results that make one processor look like a champ while another “languishes” along at 175 frames. But where’s the value in that?  Running at 1680x1050 represents a solid baseline for mainstream gamers, while 2560x1600 serves as today’s Holy Grail. Add or subtract anti-aliasing and anisotropic filtering anywhere in there for the best balance between performance and quality.

In games like S.T.A.L.K.E.R. and Far Cry 2, you see a lot of the same results, regardless of the platform on which you’re running. Those are the titles where frame rates drop perilously low—they’re limited by the GPU power plugged into their PCI Express slots. Ideally, when you add a second board and turn on CrossFire or SLI, that situation changes, performance jumps, and you get closer to approaching the CPU’s limit instead.

Other games, like Left 4 Dead and to a lesser extent Grand Theft Auto 4 (we’ve seen World in Conflict fall into this category, too), demonstrate more variance, even with one card installed. Frame rates are usually already playable, yielding less benefit when a second card is installed. These are the games that tend to be CPU-limited in some way—most playable, right up until a graphics bottleneck kicks in.

Thus, the conclusion here is pretty simple. When gaming is your top priority, buy “just enough” CPU and reallocate the rest of your budget toward graphics. In one test after another, we saw situations where a single ATI Radeon HD 4870 X2 or Nvidia GeForce GTX 285 wasn’t powerful enough to show some sort of benefit to one host processor or another. Only after adding a second card in CrossFire or SLI do you start seeing some benefit to a quicker CPU. And those are $400 graphics cards. Unless you’re planning on spending twice that on an upgrade, the point at which you’ll see GPU performance limit frame rates will come even sooner—long before integrated PCI Express or x8 links play any sort of role.

How does that apply to Intel’s new CPUs? Gamers planning on a single-card graphics subsystem will get plenty of mileage out of the $199 Core i5-750 and a $100 motherboard. Because this falls below where the Core 2 Quad Q9550 or Phenom II X4 965 BE are currently priced, we’ll have to see how Intel and AMD adjust post-launch. However, a 2.66 GHz quad-core chip capable of scaling up to 3.2 GHz in single-threaded applications is good for more than just gaming, and as a result, it looks a heckuva lot better than the two architectures it undercuts today.

One more thing: SLI versus CrossFire. Oy. In certain games, ATI simply kicks butt. Its performance with one Radeon HD 4870 X2 simply walks Nvidia’s GeForce GTX 285, despite the fact that the two models we used are priced similarly. But add a second, and in some cases SLI gets close to doubling performance, while ATI not only fails to scale well, but outright loses its lead. Left 4 Dead, Grand Theft Auto, and Crysis are three examples. ATI still wins out in S.T.A.L.K.E.R., but SLI buys more performance for Nvidia. ATI simply dominates Far Cry 2, no matter which way you cut it. Even still, we'd like to see ATI match the scaling Nvidia is getting from SLI. At least then our point that gamers are better off with a second graphics card versus a pricey CPU would be easier to drive home.

Chris Angelini
Chris Angelini is an Editor Emeritus at Tom's Hardware US. He edits hardware reviews and covers high-profile CPU and GPU launches.