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Intel Core i9-7900X Review: Meet Skylake-X

Conclusion

Intel’s market dominance burdens the company with certain expectations when it launches new hardware. Naturally, we expect more performance. And although we're quick to deride incremental updates, forward progress is what we want to see. At no point is a step backward alright in our books, and we saw a handful of those in today's tests.

Intel's mesh fabric and AMD's Infinity Fabric demonstrate how highly parallel architectures require more sophisticated interconnects. In some cases, they introduce performance regressions compared to simpler configurations that connect subsystems more directly. Remember, both companies used their previous-generation layouts for over a decade, and early implementations weren't without weaknesses that were later improved.

Most recently, Ryzen faced some puzzling performance issues at launch. More than three months later, a steady stream of firmware, chipset, and software updates has rectified a lot of the issues we initially identified. Even in this story, revisiting Ryzen 7 1800X leaves us with a very positive impression, particularly compared to Intel's $1000+ alternatives. Ryzen didn't magically become the fastest CPU out there, but it's impossible to ignore at its price point.

Enthusiasts might hope for similar improvements from Intel. After all, AMD is overcoming its roadblocks with a fraction of the R&D budget. We asked Intel if it expects software-based optimizations to fix what disappointed us, and company representatives responded that software tuning for the new architectural enhancements and cache hierarchy could improve performance. Remember, though, Core i9-7900X is based on the same micro-architecture as older Core CPUs. It's improbable that mere code updates will rectify issues introduced by Skylake-X's layout when Skylake-S and its derivatives are already well-supported.

As it stands, aggressive Turbo Boost frequencies and a re-balanced cache hierarchy go a long way to improving on Broadwell-E's minor weaknesses. When the Core i9-7900X does well, it really shines. Often, the chip beats every competitor we throw up against it, including Core i7-6950X. In other workloads, latency imposed by its mesh topology causes Core i9 to stumble. That isn’t to say performance falls off completely. But we do see anomalies unfitting of a $1000 CPU. If you're strictly a gamer, Core i9-7900X won't make you want to buy a new CPU, motherboard, and memory kit.

Enthusiasts also want to see robust overclocking capabilities, and Skylake-X does offer a higher frequency ceiling than Core i7-6950X. You're going to cope with a lot of heat in the process, though. Given Intel’s insistence on using thermal paste between its die and heat spreader for longer-term reliability, the processor can’t dissipate heat as effectively, so thermal performance becomes a limiting factor. Plan on investing in a beefy open loop if you want to push the Core i9-7900X much further than its stock frequencies.

Core i9-7900X performs well in our productivity, workstation, and HPC tests. The mesh-imposed disparities aren't as pronounced in those benchmarks. But we also have re-run Ryzen 7 1800X benchmarks to think about. Pressure to size up has pushed AMD's flagship down to $460, less than half of what a Core i9-7900X would cost. While Intel may capture the top 1% of high-end enthusiasts with Skylake-X, everyone else has to consider whether Ryzen may be the smarter buy.

Moreover, AMD's upcoming Threadripper CPU has to have Intel worried. How do we know? The X299 motherboards we used needed firmware updates to address very serious performance issues right up until launch. Intel didn't seem nearly as ready for Skylake-X's introduction as we'd expect. A number of Core i9s with even more cores won't be ready until later this year. However, it looks like Intel couldn't get the four-, six-, eight-, and 10-core models out fast enough. They'll ship later this month.

Unfortunately, this story won't be ready to wrap up until we have Threadripper to compare against. Given Core i9-7900X’s high price and performance caveats, enthusiasts should probably hold off on a purchase until we know more about the competition, even if Skylake-X looks like a bigger step forward than Intel's past HEDT designs.


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  • Pros: 10/20 cost now $999
    Cons: Everything else

    My biggest problem with this Intel lineup is that if you want 44 PCIe you have to pay $999. No, thanks. My money goes to AMD ThreadRipper.

    Good review!
    Reply
  • rantoc
    Doubt many who purchase such high end cpu for gaming runs at a low full hd 1080p resolution, i know its more cpu taxing to run lower res at higher fps but that's for the sake of benchmarking the cpu itself.

    I would like to see 1440p + 2160p resolutions on a suitable high end card (1080ti or equalent) benchmarked with the cpu as well as it would represent real scenarios for the peeps considering such cpu.

    Thanks for a good review!
    Reply
  • James Mason
    So it seems like de-lidding the x299 processors is gonna be a standard thing now to replace the TIM?
    Reply
  • elbert
    Meet netburst 2.0 that not only can hit 100c at only (4.7Ghz)1.2v on good water cooler but only barely beats a 7700k not overclocked in games. All this is yours for the low low price of 3X. Its slower than the old 6950x in a few tests with was odd.
    Reply
  • prophet001
    There's obviously a problem if the delta is that high.
    Reply
  • James Mason
    19835717 said:
    Doubt many who purchase such high end cpu for gaming runs at a low full hd 1080p resolution, i know its more cpu taxing to run lower res at higher fps but that's for the sake of benchmarking the cpu itself.

    I would like to see 1440p + 2160p resolutions on a suitable high end card (1080ti or equalent) benchmarked with the cpu as well as it would represent real scenarios for the peeps considering such cpu.

    Thanks for a good review!
    The differences would be less noticeable at higher res than 1080p, so.... you'd just see less dissimilar numbers.
    Reply
  • Dawg__Cester
    Hmmmmm. I bought a Ryzen 1700, a water cooler, Asrock B350 MB, 16gb ram 3200Mhz for $590 plus tax. I live in New Jersey. I was very nervous about making the purchase as I knew this was coming out this week but the sale prices got me. Unless you all think I got ripped off, (DON'T TELL ME). But in all honesty I have not regretted the purchase one bit!! I even managed to save enough to get a GTX 1080 FE GPU. I did have a few bumps in the road getting the system stable (about 3 hours configuring after assembly) but I am VERY happy. I used Intel primarily and never really considered AMD other than for Video adapters and SSDs.
    After reading this along with other articles and YT videos, I have no regerts as I enjoy my Milky Way and play my games among other things.
    Just my experience. I am not seeking positive reinforcement nor advice.
    I just feel very satisfied that I did not wait and cough up 3oo more fore something I could have for less. I know, I know it makes no sense.
    But come on fellas, its the computer game!!
    Reply
  • James Mason
    19835862 said:
    Hmmmmm. I bought a Ryzen 1700, a water cooler, Asrock B350 MB, 16gb ram 3200Mhz for $590 plus tax. I live in New Jersey. I was very nervous about making the purchase as I knew this was coming out this week but the sale prices got me. Unless you all think I got ripped off, (DON'T TELL ME). But in all honesty I have not regretted the purchase one bit!! I even managed to save enough to get a GTX 1080 FE GPU. I did have a few bumps in the road getting the system stable (about 3 hours configuring after assembly) but I am VERY happy. I used Intel primarily and never really considered AMD other than for Video adapters and SSDs.
    After reading this along with other articles and YT videos, I have no regerts as I enjoy my Milky Way and play my games among other things.
    Just my experience. I am not seeking positive reinforcement nor advice.
    I just feel very satisfied that I did not wait and cough up 3oo more fore something I could have for less. I know, I know it makes no sense.
    But come on fellas, its the computer game!!

    PCPartPicker part list / Price breakdown by merchant
    CPU: AMD - Ryzen 7 1700 3.0GHz 8-Core Processor ($299.39 @ SuperBiiz)
    Motherboard: ASRock - AB350M Micro ATX AM4 Motherboard ($65.98 @ Newegg)
    Memory: G.Skill - Ripjaws V Series 16GB (2 x 8GB) DDR4-3200 Memory ($124.99 @ Newegg)
    Total: $490.36
    Prices include shipping, taxes, and discounts when availableGenerated by PCPartPicker 2017-06-19 10:47 EDT-0400
    Depends on which watercooler and which ram, but not really.
    Reply
  • Jakko_
    Wow, compared to the Ryzen 1800X, the Intel Core i9-7900X:

    is about 25-30% faster
    costs 105% more
    uses 35-40% more power

    Ryzen looks really good here, and together with the temperature problems, Intel seems to be in some deep shit.
    Reply
  • HardwareExtreme
    Too little, too late. Does Intel really think that just because it has "Intel" written on it that it must be worth $200-$300 than AMD?
    Reply