Gaming CPU Shoot-Out Redux: Multi-GPU Scaling - Conclusions

Conclusions

With these results I am surprised again, but maybe I shouldn't be. There were some instances where a better CPU made a difference, but there was nothing earth shattering.

Even when looking at a much more powerful GPU (the R9 290) and setting up dual GPU configurations, CPU performance plays a minor role in overall system performance. Even though the CPU can help in several use cases, the GPU continues to be a major influencer.

I had expected (hoped) that a higher-end CPU would unlock or enable some untapped potential in these beefier GPU solutions. But that simply wasn't the case. My findings...

Widescreen - 1080p HD

• When paired with a single R7 260X, there is no discernible performance increase.
• With an R7 270X and above, there are some small increases in performance. In many instances the most noticeable increase are in better minimum frame rates.
• In several instances, when paired with higher-end graphics cards, the FX-4350 produces a noticeable performance hindrance. This is especially true in CrossFire configurations
• With a single GPU, the FX-6350 often performs on par with the FX-8350.
• Only with a CrossFire configuration does the FX-8350 provide real improvement.
• Performance improvements tend to flatten out above the FX-8350. There were a couple of instances where the FX-9370 and/or the FX-9590 slightly under-performed the FX-8350.

Eyefinity - 3x 1080p HD

• There are no discernible improvements on average frame rates with a better CPU, when paired with a single GPU.
• There are instances where a better CPU does give better minimum frame rates, but only when paired with the R9 290.
• The FX-4350 is often a performance hindrance for Eyefinity paired with GPUs in CrossFire.

General

• The higher-end FX-9370 and FX-9590 do not offer enough of a performance boost to justify the extra money, power draw and heat generation.
• The FX-4350 is performance hindrance to the R9 290, when powering a widescreen system. It is also a hindrance with any CrossFire usage.
• The sweet spot for single screen continues to be a mid-range processor such as the FX-6350.
• The FX-8350 does provide a performance boost in CrossFire applications.

Buying Recommendations

Intel

Looking back at the first article, and drawing parallels here, I would make similar recommendations for Intel CPUs. The Intel Core i3 may still be a good CPU for single screen gaming on single GPUs. An Intel Core i5 should serve well for dual GPU configurations. Assuming the extra cores perform in a similar manner, we would expect to see real improvements on the minimum frame rates with the Core i5. The additional cores will also help with the multi-tasking inherent in the PC environment.

While you're gaming, your machine is also running Windows, anti-virus, Steam, Steamspeak, and maybe a browser window. I never pushed my benchmarks with that much of a workload, but I think the Core i3 would start to suffer.

As with the FX-9370 and the FX-9590, I see no real reason to spend the extra money on a Core i7. And I would even expect diminishing returns on the higher-end Core i5 parts. In general, I don't see any evidence to support purchasing a CPU beyond the $175 - $200 range.

AMD

To put a wrinkle in this, AMD has just launched three new processors and lowered the costs on the existing CPU stack. My intent was to time the release of this article with the release of those parts, and the price reductions. I didn't have the time to test the new chips, but I hope to shed some light on where they slot in here.

Looking at only the parts I've tested here, I would continue to recommend an FX-6350 for a single screen, single GPU configuration. For single screen, dual GPU configurations, I would recommend the FX-8350.

For Eyefinity, I would recommend the FX-6350 for all configurations (again, only looking at the parts I tested), except CrossFire configurations R9 280X and above. The FX-4350 is a hindrance to performance and should be avoided for serious gaming. On the opposite end, the FX-9370 and FX-9590 don't offer added performance for the price increase (and more importantly the power draw and heat generation).

But, AMD released new parts...

Considering the new parts and prices, the recommendations change a bit. AMD has released the new FX-8370, which slots in between the FX-8350 and the FX-9370. Given the minimal difference between those two chips, I can't recommend this as a purchase. It's only 100MHz faster than the FX-8350, and will offer no real gaming improvements. The real interesting pieces are the FX-8370E and the FX-8320E. These are 8-core chips, but run at lower base clocks. The max clock falls in line with the original version, but the lower base clock makes these 95W parts.

The base clocks on these are lower than either the FX-4350 or the FX-6350, but clocks aren't the whole story. The FX-4350 runs at a higher clock speed than the FX-6350, but it consistently performs worse. The two missing cores are the driver of the performance drop. On the other side, the FX-8350 is only 100MHz faster than the FX-6350, yet it shows better performance in many cases - specifically in minimum frame rates. The additional cores drive this improvement. In fact the FX-4350 is clocked higher than both the FX-6350 or the FX-8350, but is obviously the worst performer.

Eight cores in the FX line is where you hit the sweet spot to maintain the best minimum frame rates, and process all of the data coming from dual GPU configurations. Significant clock increases don't have the same impact of adding the cores. The FX-9370 is 400MHz faster than the FX-8350, and the FX-9590 is 700MHz faster. But neither chip offers measurable real world improvements for gaming. My recommendation would be the new FX-8320E, for both single and dual GPU configurations. It offers eight cores, and plenty of clock speed.

With these cores, not only will you get the benefits of the additional cores today, but they will pay increasing dividends in the future. AMD Mantle is a highly parallel architecture, and the full eight cores will take advantage of this feature. DX12 is following in the parallel footsteps of Mantle. While Mantle will probably never get adoption as wide as DX12, the parallel nature of DX12 will ensure eight cores have a long life.

In General

Unless you're a content creator, or spend a lot of time doing specific CPU intensive tasks (such as encoding video), I think your money is better spent elsewhere. The price range on the AMD CPUs are quite narrow, and thus the savings impact may be minimal.

For example, an FX-8370 (or FX-8370E) only costs $55 more than an FX-8320E. That $55 may get you a bigger SSD, some more RAM, a better case, a GPU with a custom cooler, or a quieter CPU fan.

But on the Intel side, there is a $50 price range within just the Core i5 parts. If you drop down from a Core i7 part, you're looking at $100+ savings. This is enough to upgrade to a better class of video card, or double your SSD. These are sizable savings. Consider the savings from an "E" class CPU, and you could buy a second GPU. This would improve your gaming performance much more than the top-end processor.

I wanted to be able to tell you that the high-end CPUs would pair perfectly with high-end GPUs (one or two). I wanted to be able to say, "here is where we find the tipping point, and performance unleashes". But we don't find one, so I can't tell you that. Higher-end GPUs will match better with higher-end CPUs, system balance and all. But buying a bigger CPU just to have it won't give a noticeably improved experience. Even on their slide deck, AMD shows that they feel you need an R9 290 to warrant an FX-9370.

In Closing

I'll close by quoting my conclusions from my first article, as I think they are still relevant - even with this new data. Or maybe more-so because of the new data.

Given the newly released CPUs, I'd replace FX-6350 with FX-8320E. But the sentiment is still the same - shop smart.

What's Next

Well, I think this is the last major "matrixed" article I'll be doing like this - at least until there is some whole new system architecture. And I don't mean just the regular upgrade cycles. It would need to be something groundbreaking.

I'm glad that I have the FX-9590 in my test rig. It ensures that I'm wringing every last frame out that I can (given the hardware that I have). I'm hoping to get another R9 290, and eventually an R295 X2, as well as the new R9 285. I'd like to take a handful of GPUs, and start benchmarking how major games perform in multi-monitor, 21:9 and 4k. I want to look more towards finding what GPU you need to run the settings you want, on the panels you want.