As you're likely aware, during this year's Computex expo Intel announced the new Core X CPU series, comprising of not just three or four processors, but nine of them, making it the biggest range of high-end desktop CPUs Intel has ever announced. Today we'll finally be checking some of them out.

After years of remaining unchallenged, Intel is finally facing some serious competition with the arrival of AMD's Ryzen 7 and Ryzen 5 chips. Those parts have managed to put Intel's mainstream offerings under fire, and that's apparently just the beginning. AMD has also announced a high-end desktop series dubbed ThreadRipper, which is expected to include a chip with 16 cores and 32 threads, while costing considerably less than Intel's 10-core Broadwell-E offering.

Speaking of Broadwell-E, the sting from that series is still fresh in my mind. The 10-core 6950X came in at an insane $1,700 (now $1,450) while the 8-core 6900K wasn't much better at $1,050 (now $900). Those seeking a 6-core Intel CPU had to cough up at least $430 (now $370) for the 6800K but also sacrificed 12 PCIe lanes in the process (40 to 28).

Needless to say, Ryzen 7 made a mockery of Broadwell-E and Intel needed to counter sooner rather than later.

In its haste, the company has launched Skylake-X as a stopgap solution. However, in a world where the Ryzen 7 1700 goes for $310, it seems fair to question whether Intel can get away with charging roughly twice that amount for the 8-core Core i7-7820X, one of the new processors we're reviewing today.

Higher up the food chain is the Core i9-7900X, the most affordable of Intel's new Core i9 CPUs. At $1,000 the part is the cheapest 10-core CPU we've seen from Intel, though it remains to be seen if that's low enough to be competitive with AMD. Likewise, the company's new 6-core Core i7-7800X is priced at a more affordable $390, but that still puts it well above the aforementioned Ryzen 7 1700.

Intel's new series also includes a pair of quad-core parts, the Core i7-7740X and Core i5-7640X, though we aren't looking at these models yet. So far I've mentioned 5 of Intel's 9 new Core X CPUs, with the remaining 4 parts being premium 12, 14, 16 and 18-core models that won't be available until later in the year.

The Test

Forewarning: We've already covered specs and other related information of Skylake-X during Computex and since our coverage on this launch is a few days late, it seemed best to just get to the point. Big thanks go to Asrock who provided us with their X299 Taichi motherboard for testing along with a Core i9 chip. We got around to this review sooner thanks to Asrock since Intel's samples were awfully late.

For now we'll be focusing on Skylake-X chips with lower core counts: the Core i9-7900X, Core i7-7820X and i7-7800X which are set to become available before the end of the month. You'll learn how the three new CPUs compare, besides their core count and evident price differences, the key thing to note here are the available PCIe lanes.

For the full 44 lanes, consumers must invest no less than $1,000, while the $600 and $390 parts offer 28 lanes -- the same amount as last season's 6800K.

Next to the previous-gen 10-core i7-6950X, the Core i9-7900X looks impressive. You get the same core and thread count while paying ~40% less. You also get a few more PCIe lanes and, of course, an upgraded CPU architecture which I will touch on in a moment. Compared to 2014's flagship Core i7-5960X, you're looking at more cores and a higher operating frequency for the same price.

AMD ThreadRipper will pack up to 16-core/32-threads and is expected to cost no more than the Core i9-7900X, though official pricing is not yet confirmed. What we do know is that the ThreadRipper platform will offer an incredible 64 PCIe lanes, while the CPUs will pack a mammoth 32MB L3 cache.

Although we can't compare the new Skylake-X chips to ThreadRipper, we can see how they compare with AMD's existing Ryzen 7 and Ryzen 5 parts, so let's do that...

Ryzen System Specs
Skylake-X System Specs
  • Intel Core i9-7900X (3.3 - 4.3 GHz)
  • Intel Core i7-7820X (3.6 - 4.3 GHz)
  • Intel Core i7-7800X (3.5 - 4.0 GHz)
  • Asrock X299 Taichi
  • 32GB DDR4-3200 RAM
  • Samsung SSD 850 EVO 2TB
  • Nvidia Titan X (Pascal)
  • Windows 10 Pro 64-bit
Broadwell-E System Specs
Kaby Lake System Specs

Previously with the Broadwell-E processors such as the 6950X and 6900K we were stuck at a memory speed of about 2666MHz. The Skylake-X models happily accepted the 3600MHz Xtreme Memory Profile of our G.Skill TridentZ RGB 32GB memory kit. However, we felt 3200 was a better speed for this test until we know how many memory modules, X299 motherboards and Core X CPUs can hit this frequency.

Anyway, running the memory at DDR4-3200 resulted in a massive bandwidth of 63GB/s for the Core i9-7900X and the 6-core 7800X also achieved roughly 60GB/s of throughput. Compared to the previous-gen 10-core 9650X, the 7900X enjoyed around an 18% boost in memory performance.

Synthetic & Application Benchmarks

AMD's Ryzen 7 series is impressive in the Cinebench R15 multi-threaded test and as you can see, the 8-core CPU puts the 6900K down with relative ease. In fact, the 1800X isn't a great deal slower than the 10-core 6950X, largely thanks to greater operating frequencies.

However, the Core i7-7820 and its higher clock speeds make up for this, roughly matching the 6950X while offering almost a 20% boost over the 6900K. The 6-core 7800X also outscores the Ryzen 5 1600X -- comfortably so for the single core result.

Then we have the big daddy, the Core i9-7900X and its amazing result of 2201 points, making it by far the most powerful desktop CPU we've ever tested. The single-thread result is also impressive, landing on par with the 7700K.

Those wanting to compress and decompress archives in a hurry should take notice because again there's no desktop CPU as fast as the Core i9-7900X, at least at the moment. The 7900X was 17% faster than the 6950X in this test while it was 19% faster than the Ryzen 7 1800X when decompressing. When it comes to compression work, Ryzen isn't nearly as efficient and as a result the 7900X was 65% faster for this test.

The 6950X was always a beast in Excel, taking just two seconds to complete the workload. This isn't a memory sensitive test so all that extra bandwidth doesn't really help the 7900X pull miles ahead, but it still offered an 8% performance increase. Meanwhile, the 7820X squared up with the Ryzen 7 1800X and the higher clocked 7800X matched the 6900K.

The PCMark 10 Essentials benchmarks aren't really designed to take advantage of core heavy CPUs, rather they simulate common, everyday ways that people use a PC. The workloads from this test that we're looking at cover web browsing and video conferencing.

As you can see, the 7700K and its superior out of the box clock speed makes it the best for web browsing tasks. That said, thanks to strong single and dual-core performance the 7900X still does well, as do the other Skylake-X CPUs. The video conferencing test is more core-heavy and as a result the 7900X does pull ahead of the 7700K by an 8% margin, but it's only able to equal the Ryzen 7 1800X.

The Productivity test group measures system performance with everyday office applications, namely looking at Spreadsheets and Writing workloads. Again, not a test that takes advantage of workstation class hardware so quad-cores such as the Core i5-7600K still do great here.

The Digital Content Creation test group reflects the demands of working with digital content and media. The tests include photo editing, rendering and visualization and video editing. The graph above shows the performance of the first two test groups and a following graph will look at video editing.

As expected, the Core i9-7900X does well in these tests, outscoring the Ryzen 7 1800X by a 33% margin for the rendering test, though it was only 2% faster at photo editing, which will use far fewer cores.

Lastly we have PCMark 10's video editing results and again, editing typically isn't that taxing on the CPU and few editing applications do a good job of utilizing more than a few cores. That's certainly reflected here as the 7700K was by far the fastest CPU tested. The Core i9-7900X handled business too but it wasn't much faster than the 1800X.

Rendering and Encoding Benchmarks

Corona comes as a standalone benchmark. It renders a fixed scene six times and we measure the time it takes to complete the task. This application loves threads so the more the merrier. As you can see, the Core i9-7900X took just 97 seconds which is less than half the time it takes the Core i7-7700K, it's also a 34% improvement over the 1800X. The 7820X was roughly on par with the 6950X while the 7800X was slower than the 6900K but did out-edge the Ryzen 5 1600X.

Blender is a popular application and is often used for benchmarking CPU performance by both AMD and Intel. The open source software is free to download and I used version 2.78 along with AMD's Ryzen render file for the workload, so yeah these new Intel CPUs are rendering Ryzen CPUs, hmm... Anyway, the Core i9-7900X didn't seem to waste anytime pondering the implications, completing the job in a blistering 18 seconds. The Core i7-7820X took 21.5 seconds and the 7800X was done in 26 seconds -- rather strong performance from the new Intel CPUs.

For our HandBrake test we take a 4K high quality video file and convert it from H.264 down to 1080p using HEVC, also known as H.265. The numbers you are seeing in this graph show how many frames per second each CPU was able to transcode the video at. The Core i9-7900X is a beast, with its 30.7fps being 31% faster than the 6950X and 51% faster than the Ryzen 7 1800X. The higher clock speed of the 7900X really helps here though the added memory bandwidth is equally important.

Even the 7820X is able to pull ahead of the 6950X, beating it by a 9% margin, remember this is an Intel 8-core part versus their previous generation 10-core part, so mighty impressive stuff. Intel's the 6-core 7800X was about equal to the 6950X.

Right, so this is the test I care most about as I spend quite a bit of time each day rendering videos, to the CPU that can save me the most time here is generally the one I use. For example, the PC used to render this video packs a Core i7-6950X and I had planned to probably replace it with ThreadRipper.

That said, the current version of Premiere Pro CC isn't that good at taking advantage of high core count CPUs and as a result the 7900X is just 4% faster than the 6950X, so a bit of a disappointing result here. This benchmark is CUDA accelerated by a GTX 1080 Ti so keep that in mind, though there aren't a huge amount of effects in my videos for the GPU to accelerate.

Gaming Benchmarks

I get these aren't gaming focused CPUs but if I skipped over the games I can't imagine it would go down to well with many of you, so I've picked four CPU-intensive games that do as good a job as any of utilizing cores. That said, most are best handled by a 6-core/12-thread CPU. Battlefield 1 for example still hits the highest frame rates on the Core i7-7700K -- still, for a core-heavy CPU the 7900X performs great, and so did the 7820X and 7800X.

Mafia III was one of the few games that really took advantage of Ryzen when it was first released, allowing AMD to enjoy strong gains over the 7700K in this title. However, the game was quickly patched to either become less CPU intensive or better optimized, I'm not sure, but the direct result was lower CPU utilization while achieving slightly better frame rates. Here we see that the game still favors the higher clocked 7700K but also still requires more than four threads as the 7600K is quite a long way down our graph.

Hitman is a surprisingly CPU demanding title. Please note I've tested using DirectX 11 to avoid the issues Nvidia GPUs seem to have with Ryzen when using DX12, though I haven't revisited this recently. Anyway, the Skylake-X CPUs perform well, though again it's the 7700K that's the fastest option here.

Finally, we have Ashes of the Singularity, the only game that can really take advantage of 10-core CPUs, though at this point it's more of a synthetic benchmark than a game anyone actually plays. Nonetheless, it give us an idea of what future games might require, though how far away that future is anyone's guess.

Overclocking, Power & Temps

Up until now the new Syklake-X processors have looked mighty impressive. The 6-core 7800X sucks down the same 193 watts as the 8-core Ryzen 7 1800X -- I was hoping it would be closer to the 1600X. Still, the 7800X isn't really the issue, both the 8-core and 10-core models are considerably more power hungry.

Both pushed system consumption over 200 watts and that's significantly more power than what the 6950X system used. 226 watts is a huge amount of draw for the Excel test, let's move on and see what the power consumption figures for the Cinebench R15 test look like.

Okay so these numbers are even worse, quite a bit worse. The reason for this being that the Cinebench R15 test is not just more intensive, but it also runs for quite a bit longer so the chips heat up more and consume even more power. For this test the 7900X was sucking down almost 260 watts whereas the 6850X hit just 212 watts. Clearly those higher clock speeds come at a real cost.


Although our coverage is late we still haven't had much time to play with the new Core-X CPUs. They arrived only a few days ago so I've yet to do much overclocking beyond the 7900X. The results were mixed. My chip only managed a stable 4.6GHz and no matter how much voltage I threw at it I wasn't able to stress test . The system would boot into Windows but would blue screen within the first few moments of running a stress test. Stability might improve with future BIOS updates, or perhaps I just have a bit of a dud. Looking around the Internet it seems some are stuck at 4.6 GHz like me while others have managed to stabilize their system at 4.7 or 4.8 GHz.

The results were mixed, my chip only managed a stable 4.6GHz overclock, no matter how much voltage I threw at it I wasn't able to stabilize anything beyond that. The system would boot into Windows but would blue screen within the first few moments of running a stress test. Stability might improve with future BIOS updates, or perhaps I just have a dud. Looking around the Internet it seems others are also stuck at 4.6GHz like me while some folks have managed to stabilize their system at 4.7 or 4.8GHz.

However, the frequency isn't my greatest concern right now. Using just 1.2 volts, which is all I needed for a stable 4.6GHz overclock on all cores, the system consumption went from the 259 watts just seen to an insane 402 watts! That might not even be the worst part, the deal breaker is probably the operating temps. Chilling the 7900X was Corsair's H100i v2 and despite being a premium 240mm AIO liquid cooler, temps skyrocketed as the CPU was place under load, reaching 90 degrees instantly before climbing further towards 100 degrees. Unless you have an amazing cooler, I'm not sure overclocking is going to be worth it.

Analysis: Price vs. Performance and Takeaways

Before jumping to conclusions, let's try putting our results into perspective with a price vs. performance scatter plot for the Cinebench R15 multi-threaded results. Ideally, for all the price vs. performance graphs here you want the CPU to be as far right as possible and as low as possible, the further right the better the performance and the lower the better the price.

As you can see, the Ryzen 7 1800X is rather far right and still quite low, looking a bit better than the Core i7-7800X in terms of value. Remember, the 1800X itself isn't a particularly good value sitting next to the Ryzen 7 1700, which sadly we didn't have time to add to this review but will in future articles.

Compared to the 6950X, the new 7900X is a massive step forward in terms of value offering much greater performance at a much better price.

Moving to the Blender results we again see that the Ryzen 7 1800X and Core i7-7800X are similar in terms of value, though again the pesky Ryzen 7 1700 will mess things up for Intel here. Anyone looking strictly at Intel’s line-up will see that the 7900X is a huge leap forwards, priced alongside the 6900K it offers significantly better performance in this application.

The Core i9-7900X proves a very significant upgrade over Broadwell-E in our Handbrake test. For the same money you're essentially getting a 50% boost in performance, I believe the increased memory bandwidth really helped here. Meanwhile the Ryzen 7 1800X finds itself situated between the 7800X and 7820X in terms of price and performance.

The Corona price vs performance figures look particularly impressive for the Ryzen 5 1600X as it sneaks in just behind the Core i7-7800X at a much lower price. Meanwhile, the 1800X is much closer to the 7820X while again coming in at a lower price.

For 7-Zip I have only looked the decompression results and AMD does much better here when compared to the compression testing. That said, I feel most of you will do significantly more decompression work than compression and as you can see for decompression, the 1800X is a lot better value than the Core i7-7800X and 7820X processors.

Looking at the PCMark rendering and visualization figures we see that the Core i9-7900X is a massive upgrade over what Intel was previously offering, but for less than half the price the Ryzen 7 1800X isn't much slower and in terms of value it also gives the 7820X and 7800X a hard time.

Lastly we have the Premiere Pro CC results and here the scatter plot looks quite a bit different to those seen previously as this application doesn't really do a good job of utilizing the higher core count CPUs. Even so, the 7900X does still offer a decent increase in value over the 6900K.


I think we can all agree that Skylake-X offers mighty impressive performance. The Core i9-7900X blows everything else out of the water and the 7820X does a good job of making Intel's previous-generation 8-core CPU look a little sluggish. Single and dual-thread performance is great, roughly on par with the best quad-core CPUs.

After testing Intel's new 6-, 8- and 10-core parts, we're keen to check out the pricier 12, 14, 16 and 18-core editions later this year, but let's not worry about those for now.

Power consumption appears to be the only hiccup for these chips, which burned between 20 and 40% more power than the equivalent Broadwell-E parts -- pretty brutal.

Although I haven't delved too deep into overclocking yet, based on what I've seen so far I wouldn't get my hopes up, and if go-to AIO liquid coolers aren’t cutting it, serious custom loops will be required.

To recap: performance is good and power consumption is scary, but what about the price?

Compared to Broadwell-E, Skylake-X is a far better value. We've gone from $1,700 for Intel's exclusive 10-core chip to $1,000, and in the process we're getting a much faster processor, albeit a hungrier and hotter one, too.

The Core i9-7900X is still seriously expensive, but with no competition in front of it, Intel can get away with that for now. ThreadRipper will likely change that soon, which is a relief to say after so many years, but that will be a story for another day.

Let's talk 8-core CPUs for a minute. The Ryzen 7 1800X costs $460, but smart shoppers will opt for the much cheaper $310 1700, which can be overclocked to achieve the same performance. The Core i7-7820X comes in at $600, making it 30% more expensive than the 1800X, but almost twice the price of the 1700.

Looking at the Cinebench R15 multi-threaded performance, the 7820X is around 30% more powerful than the 1800X, so the price seems justified. However, moving to real-world applications, the 7820X was more like 10% faster overall.

The 7820X does have the advantage of 28 PCIe lanes versus 16 for the Ryzen 7 CPUs. Although this is something ThreadRipper will address, for the time being the 7820X is the obvious choice if you need the extra lanes.

If all you care is value, Ryzen 7 is the obvious option as decent X370 boards start at $110, making the CPU and motherboard combo just $420 if you intelligently opt for the R7 1700. Comparatively, the 7820X and the cheapest X299 board will set you back $830, basically twice the price for nowhere near twice the performance.

Likewise, the 6-core 7800X roughly equals the 1800X in terms of performance. If you throw the R7 1700 into the mix, even Intel's most affordable Skylake-X CPU is a tough sell.

Now, if you don't care about value, the Core i9 7900X is the way to go. Its performance is exceptional, you get loads of PCIe lanes, overclocking is an option to some degree (quite a few degrees in fact) and the X299 platform is superior to AMD's X370. But if you can wait a couple of months, my advice is to hold out and see what AMD has to offer with and then go from there -- if nothing else, Intel might have to adjust pricing.

Shopping shortcuts:

Intel Core i9-7900X on Amazon, Newegg

Asrock X299 Taichi motherboard on Newegg

Intel Core i7-7820X on Amazon, Newegg

Intel Core i7-7800X on Amazon, Newegg


Pros: Skylake-X topped our performance charts, bringing a much better value over Broadwell-E on the high-end.

Cons: It's extremely power hungry and considerably more expensive than Ryzen equivalents.