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

Bringing Out The Big Guns

With the launch of P55 and Intel’s three LGA 1156-based CPUs, we wanted to revisit the topic of gaming performance. However, we couldn’t do it in quite the same way. You see, whereas X58 serves up to 36 lanes of PCI Express 2.0 connectivity, P55 only boasts eight—and those eight aren’t even meant to accommodate graphics cards, since the chipset communicates with its host processor via Intel’s Direct Media Interface (DMI). The company won't say how fast this generation of DMI is running, but it's not fast enough for serious gaming.

Thus, we only have the CPU’s 16 lanes of on-board PCI Express 2.0, which can be used as a single x16 link, split up into two x8 links, or multiplexed via something like Nvidia’s NF200 bridge into additional x8 links. That third option is a little extreme for a platform aimed at a mainstream audience though, so we’re going stick with single- and dual-card configurations here.

The FU Edition, only from BFG.

ATI’s Radeon HD 4870 X2 remains the company’s fastest board (almost a year later, even), but Nvidia now offers the GeForce GTX 285 and GeForce GTX 295. While we don’t have a second GTX 295 in-house, we got our hands on the next best thing: a pair of BFG’s GeForce GTX 285 OCFU Edition cards, which work out well because they cost just about as much as the dual-GPU Radeon.

So Many Variables!

Comparing performance results in a story like this, and then identifying the cause underlying frame rate dips and spikes can be a challenge, as we’re testing a range of different CPU architectures and platforms that do different things with PCI Express.

There are a lot of miles on these puppies...

Fortunately, we spent some extra time normalizing the clock speed of today’s most popular enthusiast architectures and comparing the effect of integrated PCI Express 2.0, a pair of chipset-based links full x16 signaling, and chipset-based links at x8 signaling rates in our story In Theory: How Does Lynnfield’s On-Die PCI Express Affect Gaming?

The general conclusion there was that we do see theoretical advantages to running one graphics card on an integrated x16 link. However, that benefit does not translate to real-world gaming. And when you add a second graphics card, halving the on-die link to create two x8 connections does hit performance a bit in environments that are platform-limited. Of course, as you get closer to 2560x1600 with anti-aliasing enabled, the benefits of CrossFire and SLI are sufficient to mask that architectural compromise.

At the end of the day, you end up with what amounts to a wash at high resolutions with one card installed. With two, even at 2560x1600, the pair of dedicated x16 links turns out slightly better results.  Is that enough to warrant a pricy X58 motherboard and Core i7 processor? With everything running at a constant 2.8 GHz, not really.

But let’s shift away from our theoretical look at performance and get all of these processors running at their retail speeds for a more real-world look at gaming using ATI’s CrossFire and Nvidia’s SLI in Intel’s new P55.

  • lashton
    so we can assume for gaming the 965BE (or 955 oc) and ATi cards are just as fast as Core i7 and i5 but at a fraction of the price
    Reply
  • cangelini
    The 955 does cost less. The 965 is more expensive than Core i5.
    Reply
  • Dekasav
    Only thing I don't like is how you knock Crossfire with 2 HD 4870X2's, since when is it even feasible that 4-way CF would scale as well as 2-way SLI?

    But excellent review, overall, I'm actually surprised at how the 965BE did, I thought it'd be behind, where it was actually right in the pack.
    Reply
  • dirtmountain
    I would have liked to see a 780a or a 980a SLI motherboard used to check the SLI numbers on the P2 965BE. I'm also surprised there's no overclocking numbers in the comparison, is that article still to come out?
    Reply
  • cangelini
    It's upcoming dirt; Patrick is the one working on it (and our Italian team sent word of its i5 and i7s in excess of 4.2 GHz)
    Reply
  • sudeshc
    Nice game collection you got there.......:)

    Great review.
    Reply
  • anonymous x
    Let us know what you think about this in the comments section, but it was pretty clear that Vista was never a favorite, so we're hoping Windows 7 is a more popular environment in which to test
    I like vista, rock solid and stable since I got it years ago. Don't listen to the bashers who never have tried the product.
    Reply
  • lashton
    You giotta remember vista is design for spoecific hardware and powerfull hardware that can run it, so people with P4 3GHz and vista complain about its speed, vista is OK, i dont like it cause my computer doesm't like it thats fine i get over it and chnage my OS
    Reply
  • cangelini
    Thanks for weighing in, guys!
    Reply
  • crash27
    So there's no benafit from adding a second 285 to a q9550s or an x4 965 be ??

    I get a good performance boost from my second gtx280 with my q9650 @ 4 gz
    Reply