FX Vs. Core i7: Exploring CPU Bottlenecks And AMD CrossFire

By Thomas Soderstrom
published

AMD and Intel continue serving up increasingly faster CPUs. But graphics card performance is accelerating even faster. Is there still such a thing as processor-bound gaming? We take two Radeon HD 7970s, high-end desktop CPUs, and a few games to find out.

Skyrim, Frame By Frame

As mentioned, our frame-time measurements come from Fraps, which isn't necessarily ideal given the work that happens during the CrossFire pipeline, and where Fraps derives its data. So, we wanted to at least run a second title to gauge whether the numbers and "feeling" aligned. Charting these values tells us more than the worst frame time; it adds how often and where they're occurring during the benchmark.

The benchmark that seems best-optimized for Intel's platform, Skyrim already appears devastating to AMD's FX-8350 at a mere 1920x1080. We're hoping that this artifact is a little easier to tolerate in an RPG, but spikes above 70 ms are certainly jolts you can "feel" while you're playing.

The FX-8350 gets hammered even harder at 4800x900, and the difference between AMD and Intel CPUs tells us that the graphics subsystem isn't to blame. Regardless of where Fraps takes its measurement, we simply cannot ignore the notably-higher spikes on AMD's flagship.

Both the AMD and Intel platforms fail our 50 ms upper limit at 5760x1080, at least when the game is set to the High quality preset. Somehow, the Core i7-3770K ducks in under 50 ms throughout the test using Ultra quality settings, showing far smaller spikes, even as its average frame time increases.

Thomas Soderstrom
Thomas Soderstrom
Thomas Soderstrom is a Senior Staff Editor at Tom's Hardware US. He tests and reviews cases, cooling, memory and motherboards.
164 Comments Comment from the forums
  • A Bad Day
    We were hoping that AMD's Piledriver update would break that trend, but even a handful of impressive advancements aren't enough to match the effectiveness of AMD's graphics team. Might Steamroller be the evolutionary step forward needed to unleash the GCN architecture's peak performance?

    I disagree. What's needed is even stronger push on the developers to use more than four cores, effectively, not some 100% load on one core and 10% on the other five cores.
    Reply
  • acktionhank
    Great article and very informative. The FX-8350 really held it's own until it came down to Skyrim.

    A Bad DayI disagree. What's needed is even stronger push on the developers to use more than four cores, effectively, not some 100% load on one core and 10% on the other five cores.
    I thought more cores were for multi-tasking, as in having multiple programs running simultaneously. It would suck to turn on BF3 and everything else running on my PC simply shut down because the CPU is under 100% utilization. How would i be able to play BF3 while streaming/playing some HD content on my TV that's hooked up to my same computer.


    Reply
  • alidan
    acktionhankGreat article and very informative. The FX-8350 really held it's own until it came down to Skyrim.I thought more cores were for multi-tasking, as in having multiple programs running simultaneously. It would suck to turn on BF3 and everything else running on my PC simply shut down because the CPU is under 100% utilization. How would i be able to play BF3 while streaming/playing some HD content on my TV that's hooked up to my same computer.
    single core performance... look up some other benchmarks, where they use itunes to encode things, or when i believe winzip went from single core to multicore, it shows a GREAT difference more cores can do to performance.

    the problem is that few games and few programs really scale, sure, pro applications almost always take advantage of whatever you put in them, but consumer, different story.

    more cores can offer more multitasking, but they also allow the load to be shifted from one core to all 4 cores and get over all more performance when properly coded.
    Reply
  • Someone Somewhere
    Personally I'd like to see the i5-3570K included in here. It's closer in price to the 8350, but should perform more like the 3770K (as the games are unlikely to use more than 4 threads).
    Reply
  • Crashman
    A Bad DayI disagree. What's needed is even stronger push on the developers to use more than four cores, effectively, not some 100% load on one core and 10% on the other five cores.I'm calling BS on this one because AMD's "eight cores" are actually four modules, on four front ends, with four FP units. Games have historically been limited by FP units specifically and front ends in general, no? What I'm seeing is that Intel's per-core IPC appears to be a little higher, when two different FOUR "full" CORE processors are compared.
    Reply
  • esrever
    There should be an i5 included just so you can have a middle ground.
    Reply
  • amuffin
    I'm really liking the new logo!
    Reply
  • de5_Roy
    like the article.
    woulda liked to see how a 3570k does against the fx8350 running the same cfx setup. impo, the price/perf woulda tipped further in favor of intel in configs like this.
    lastly, woulda liked some newer games like sleeping dogs, far cry3, max payne 3 in the benches instead of the ol' bf3 single player. i hear bf3 sp doesn't stress cpus that much. may be bf3 skewed the benches in favor of amd as much as skyrim favored intel. :whistle:
    Reply
  • quark004
    all these benchmarks are manipulated. First, there is this site which claims the 7900 series does well even with mid level cpus in gaming scenarios. And now toms claim a high end cpu. There is some propoganda here.
    Reply
  • abbadon_34
    It would be nice to see prices for components similar the SMB. Not because I can't look them up, but because the article is very price/performance oriented
    Reply