In Theory: How Does Lynnfield's On-Die PCI Express Affect Gaming?

Benchmark Results: 3DMark Vantage

Early on, we see some genius to the way Intel has implemented PCI Express on Core i5—at least for gamers using a single card.

If you compare i5 to i7 using one Radeon HD 4870 X2, scores are consistently higher at each of our three test settings. Core i5 is even able to beat the 2.83 GHz Core 2 Quad, which, clock for clock should be faster in many gaming situations (and sure enough, in two of the three 3DMark runs, Core 2 Quad is faster than Core i7, but loses all three to Core i5). Phenom II edges closer as the details increase, but only really bests Core i7 in the overall metric.

Add a second card, though, and the situation changes a bit. Suddenly, Core i7 jumps into the lead, bolstered by its two PCI Express x16 links. Core i5 extends its lead over Core 2 Quad—presumably since its Radeon HD 4870 X2s are leveraging on-die PCIe connectivity, while the P45’s twin eight-lane links are forced to communicate over a 1,333 MHz front side bus.

At 2.8 GHz, the Core 2 Quad and Phenom II trade blows. Nothing notable though, since they both lose out to Core i5.

A more telling gauge of graphics performance, the GPU score represents a weighted arithmetic mean of the raw scores taken from each of the two graphics tests in Vantage. As you can see, with a single card installed in each platform (thus, all contenders getting 16 lanes of PCIe 2.0), the Core i5 is the fastest, clock for clock. Clearly, the on-die connectivity is working to its benefit.

Add the second card, though, and the inflexible x8/x8 design actually turns into a detriment, as the X58’s dual x16 links allow it the lead across the board. The good news for mainstream gamers who weren’t even considering X58, however, is that Core i5 is still able to best Intel’s Core 2 Quad and its P45 platform. Incidentally, in two of the three tests, AMD’s Phenom II X4 920 also slides past the Core 2 Quad (falling short of the i5).

Consisting of an AI test and a physics test, both parallelized, we see the Core i5 and Core i7 roughly on par, with the Core i7 trending just a tad higher overall. However, both CPUs beat Intel’s Core 2 Quad, which in turn bests the Phenom II X4. Of course, the results in a synthetic metric like this one are subject to myriad optimizations and only really derive meaning from parallels to real-world proof points. So let’s get into a couple of real games and see how this initial analysis pans out.