Intel Skylake-X Core i7-7800X Review – The True HEDT Entry-Point?

👤by Tim Harmer Comments 📅29-06-17

We made no secret of not being particularly impressed by the Core i7-7740K, our introduction to Intel’s Core X/X299 platform. The SKU struggles to find its place in the market due to similar performance compared to the mainstream i7-7700K but none of the unique features we typically expect from Intel’s HEDT platform. The question is, can the Core i7-7800X present a true entry point that realistically matches up with the Intel High End Desktop pedigree.

Well, as always, the picture is mixed.

Perhaps the first point to make clear is that we didn’t observe any clearly anomalous gaming results in the limited testing performed. Poor gaming performance was reported early with the preliminary Skylake-X reviews prior to launch, mainly attributed to clearly buggy BIOS implementations, but for our AUROS X299-GAMING 3 any critical issues appear to have been eliminated. So, very good news for gamers, especially when coupled with firmly middle of the pack results.

Synthetic performance was all a little more erratic, especially compared to the somewhat predictable performance of Haswell-E and Broadwell-E. Often it leapfrogged 8-core Haswell-E and Broadwell-E CPUs in specific tests, highlighting quite a substantial practical difference between CPU architectures.

Curiously, the i7-7800X failed to really distinguish itself against AMD’s Rysen lineup in many synthetic and real-world tests, but generally prevailed over its 6-core AMD Ryzen 5 counterpart. Clearly we should bear in mind that tests were performed at stock speeds though, and few tests would be able to take full advantage of the i7-7800X’s immense memory bandwidth.

Speaking of memory bandwidth, we should note that SiSoft Sandra appeared to fail to leverage the quad-channel memory of this CPU. That’s in contrast to AIDA64, which achieved far more robust numbers with the same system configuration (although below that of the Broadwell-E 8 and 10-core SKUs). The reasoning behind this is unclear, and we eagerly await additional Skylake-X samples to see if this pattern replicates.

Of course, the 7800X is also a 28-lane PCI-Express 3.0 part, but that is in no way captured in our general CPU reviews. The market for this feature is exceptionally narrow, and narrowing all the time as manufacturer support for multi-GPU configurations diminishes, but applications which push the boundaries or systems with exotic PCIe storage could benefit from it over the 16 lanes on Kaby Lake/Kaby Lake-X.

Perhaps the most exciting result is that headline overclocking high watermark. Hitting 4.8GHz - 33% over stock mind - almost effortlessly is eye-opening, and indicates that there’s a lot of potential sitting in the pocket of this CPU unused. Nonetheless hitting 90C overclocked on a pretty hefty Closed Loop Liquid Cooler is far from ideal, and larger Skylake-X CPU dies with more active cores could quickly exhibit runaway temperatures when overclocked to this level. That certainly tallies well with other reports of the current 10-core flagship.

So, what conclusion can we come to? The picture would be far simpler were AMD’s Ryzen lineup absent – the Skylake-X architecture is a small but not insignificant step forward over Broadwell-E that may still see further software and BIOS optimisations to take full advantage of. It's no secret that the launch was brought forward to combat AMD's Threadripper, so a few teething issues are to be expected. Nonetheless the i7-7800X finally feels like a proper entry to the HEDT platform compared to the Kaby Lake-X chips, and if mixed workloads including video encoding are part of the plan then the 7800X is a meaningful upgrade over the mainstream Kaby Lake platform.

Ryzen, especially the Ryzen 7 1700, is the spanner in the works. Synthetic multicore performance for AMD’s new chips is more than solid, and gaming doesn’t appear to suffer too much versus the 7800X due to the latters’ relatively low stock clocks. The relative affordability of AMD's platform could be a deal-maker over the i7-7800X if the intention is merely to run the CPU at ctock speeds, mainly due to the cost of X299 motherboards.

In general, Intel’s Core i7-7800X’s market will be hobbyist overclockers, overclocking gamers with moderate video rendering speed requirements, or Intel loyalists who particularly appreciate the HEDT platform. £350 for an OEM CPU is a steal compared to a stock 7740K if you even venture into the motherboard BIOS for more than a few minutes, and in that respect it’s more fun to boot.

A true entrance point for this generation of Intel’s HEDT platform, the Intel Core i7-7800X is the cheapest Core X CPU we’d probably be happy to buy. Although it doesn’t excel in multi-core workloads, and modest stock frequencies undersell the CPU’s potential, mixed workloads and a penchant for overclocking will really allow this CPU to shine.

+ Creditable stock performance
+ Good stock thermal performance
+ Overclocks exceptionally well
+ Quad-channel memory support
+ Full range of HEDT features
+ Only £40 more than the i7-7740K

- Outpaced by many 8-core CPUs in heavily multi-core workloads
- Costly platform compared to Z270/7700K and Ryzen

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