Intel Core i7-8700K and Core i5-8400 Processor Review – Coffee Lake

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Memory Bandwidth Benchmarks

SiSoftware Sandra 2016 SP3 Memory Bandwidth: link

SiSoftware Sandra 2016 is a utility, which includes remote analysis, benchmarking and diagnostic features for PCs, servers, mobile devices and networks. This test has been popular for CPU and memory benchmarks for well over a decade and it is one of the easiest benchmarks out there to run.

sandra 8700k

Memory Bandwidth Results Summary: The Intel Core i7-8700K processor with the Corsair Vengeance DDR4 3000MHz memory kit with CL15 timings gave us about 32.6 GB/s of memory bandwidth on Sandra. This is about 1 GB/s higher than we got with the same exact kit on the Intel Core i7-7700K processor, so we are happy with that. The issue we ran into was actually on the Intel Core i5-8400 processor. On the Gigabyte Z370 AORUS Gaming 7 motherboard with BIOS Version F4a we were unable to run anything higher than 2666MHz memory for some reason. We tried both sets of slots, manual and XMP settings and eventually five different memory kits from Corsair and G.Skill. We reached out to Gigabtye and other reviewers and found that some weren’t having issues and others were on this board and processor, so we’ll be looking into that closer after launch.

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  • Jake40563

    I really hope that reviews are unbiased, however I noticed that power consumption of 8700k in overclocked mode was completely ignored or I may say omitted, why????

  • goldstone77

    It takes ~1 hour for liquid in a 240mm liquid cooler to absorb heat and become saturated. How does 5 min. AIDA64 show real world temperatures that the average user would find if he would run blender or handbrake for 1+ hours? How do you factor in the all core turbo boost of 4.7GHz and 145W into this equation for helping people come up with a proper cooling solution? 95W TDP hahaha

    • Nathan Kirsch

      So, the liquid in the cooler warms up a bit more than this. It’s not worth the time doing it when there are thousands of case and cooler options out there. We test on an open test bench anyway, so all of our temperature results are going to be different than most of what the readers will see at home. We quickly look at temps and move on. This is a CPU review and not a CPU cooler review!

      • goldstone77

        I agree that a CPU review should be about the CPU. But the cooling solutions and motherboard settings involved do change the results of tests, and I believe this should be noted in the review for clarity and transparency. So, in respect to your viewers do you feel it important to convey to them that your tests will vary from real world situations that the average user would encounter at home? As a viewer I would like to see statements like this incorporated in future reviews. Also, I wouldn’t mind seeing some real world scenarios with testing in a case with typical fans and using an air cooler with the processors TDP rating, and with the full array of motherboard settings. Just my 2 cents.

  • goldstone77

    Why did you disable turbo boost for your temp test, and enable it for your performance tests? You do realize that you are getting an all core turbo or 4.7GHz consuming 145W, and saying that the 8700K falls in line with your expectations of a 95W TDP. Gamers Nexus “Multi-core “enhancement” options are either enabled, disabled, or “auto” in motherboard BIOS, where “auto” has somewhat nebulous behavior, depending on board maker. Enabling multi-core enhancement means that the CPU ignores the Intel spec, instead locking all-core Turbo to the single-core Turbo speeds, which means a few things: (1) Higher voltage is now necessary, and therefore higher power draw and heat; (2) instability can be introduced to the system, as we observed in Blender on the ASUS Maximus X Hero with multi-core enhancement on the 8700K; (3) performance is bolstered in-step with higher all-core Turbo.”

    • Nathan Kirsch

      Testing was done on the Gigabyte Z370 Gaming 7 motherboard and we left multi-core enhancement to the default setting of ‘auto’ and that is off. This is not a CPU feature and is an overclocking feature done by the board makers. We did try multi-core enhancement with the 8400 on the Gaming 7 and found that it flat out didn’t work. Gigabyte Taiwan confirmed this and is fixing it for the next UEFI release. Since multi-core enhancement is not an Intel feature and varies between board manufactures the decision was made not to cover it. Multi-core enhancement in our opinion should be put in motherboard reviews when dealing with overclocking.

      • goldstone77

        Thanks for sharing that information. Jayz2cents ended up making another review after finding out his motherboard has “Multi-core enhancements” enable on the auto setting. And was told by the manufacturer it was turned off on auto setting. He confirmed to them it was in fact turn “on”. They said they will be putting out a bios change to disable it on auto.

  • IntelAMDNvidia
  • Dorian Kunch

    Really want to thank you Nate for including the old i7-2700 in the review. I have been holding out for that magical 2x the speed thing to manifest, probably there are others too. And it’s all gotta work; games and video processing.

  • Six_Tymes

    waiting for an 8350K