More cores for the people: Coffee Lake-S with Intel Core i7-8700K and Core i7 8700 in review

For example, you currently only launch two CPUs per class, each with two more cores. If the Core i7 has 6 cores and SMT, which allows 12 threads, the Core i5 can still have 6 cores without SMT. The Core i3 is... The Z370 chipset At first glance, not much has changed about the chipset itself, except that Intel has now reopened up to AMD and has the top three in the nomenclature. PCIe connectivity remains unchanged at 16 Lane... In the AI test of Civilization IV, all CPUs position themselves in a good way as one might expect from the technical data. Even with the Time Spy CPU test, the world of the advertised hierarchies is (almost) still in order. Positive falls here ever... For this benchmark, the Core i7-8700K is exceptionally just ahead of the Core i7-8700, albeit only at average frame rates. The differences are so small that you could almost push everything into the tolerance range. The... Even if a GPU limit is not to be denied here, the CPUs still scale up to a good 140 FPS. However, the overclocked Core i7 of both genrations will no longer bring any extra power, as you can see well on the Min-FPS. ... In Civilization, the overclocked Ryzen 7 1800X can still keep up quite well. Otherwise, the Core i7 are the dominant CPUs in this selection. However, the Core i7-7800X is the inglorious exception, as it still sorts itself behind the... Clock precedes core count and the Core i7-8700 is faster than the K-Pedant. Which brings us to the paradox of our foreword to the tests, where a CPU with nominally lower turbo clock suddenly performs better than the actually more expensive Mo... Project Cars offers a very similar image, in which the non-K model performs a tick faster. The AMD CPUs, on the other hand, have no chance and are clearly behind. Individual results of all maps Other game - same image, except that this time even the older Core i7-7700K can push itself in front of the Core i7-8700K. However, if you run at overclocked to 4.9 GHz with the same clock, the Core i7-8700K is faster again. This shows... This benchmark is effectively in the balance between the two new Core i7, while the core i7-7800X, the core i7-7700K (unclocked) and the AMD CPUs have to be significantly behind. At the same clock, the speed limit is suddenly 4.9 GHz ... In this game, the focus is on the Frame Times and the Min-FPS as a logical consequence. Otherwise, the Core i7-8700 is again a tick faster. The rest repeats itself as well as with the other benchmarks. Single... Important preliminary remark on CPU selection and overclocking Contrary to our usual handling, not benchmarking the productive areas with overclocked CPUs, as it is also rather unlikely in reality, this time we have both Coff... 2D Performance In order to better understand some of the later results, we are putting forward a good old acquaintance. With our GDI/GDI+ benchmark, we are first testing two different output methods for 2D objects, how to... CPU Performance: Workstation Of course, in the production area, not only the 3D graphics performance is important in the production area for the just-set applications, because many things are calculated by the CPU in parallel within these applications (Simu... For these test series, we use benchmarks from the rather versatile SPECwpc suite for workstations, which rely on very different mathematical calculations, which on the one hand can be perfectly parallelized and where it is at the same time a... Overclocking First of all, we are exploring the limits. To make sure that we don't run in thermal limits, because Intel still relies on the tiresome thermal paste between Die and IHS, we initially use the chiller again and cool the... Summary First of all, we would like to thank AMD and their Ryzen family. Without this wake-up call or food for thought, Intel would probably have continued to delight us with now boring four-cores in the consumer sector. But that's how the train-zwan brings...

Overclocking

First of all, we are exploring the limits. To make sure that we don't run in thermal limits, because Intel still relies on the tiresome thermal paste between Die and IHS, we initially use the chiller again and cool the IHS with a constant 20°C. We reach the 5 GHz mark without any problems, which is not surprising after the experience with Kaby Lake. With 5.1 GHz Windows started and two games were running, but then Cinebench was already finished.

In this context, we would like to draw attention to the possibilities of manual load-line calibration, also with regard to the temperatures to be analyzed later. Depending on the board, you can use different levels or Select preferences or manually experiment with the voltages. This allows the core voltage to be significantly lowered under full load without sanoining performance as long as the chip plays along. With our tested board, this means with Prime95 and standard clock that the effective voltage can then be between 1.28 volts maximum and 1.18 volts, which means almost 8°C less temperature on the package.

However, it is important to note that many memory kits with a load line set too low come into the swim and become unstable. A crash is then the logical consequence. Of course, this depends heavily on CPU quality. This then concerns our overclocking with 5.0 GHz, which we did not really get there for the long term. While all games and most workstation applications ran for hours, Creo3 and some HPC applications crashed in just a few minutes.

One should therefore not be blinded by the supposed overclocking successes of the i7-8700K from time to time above the 5 GHz mark, because often enough these values have not been tested over long time and with appropriate applications. In case of doubt, it is better to take back 100 MHz and put stability in the foreground.

If we also look at our diagram with the comparison of power consumption and performance, then we already see the kink, which starts from approx. 4.8 GHz. While the power consumption continues to increase at higher clock rates, the performance is already starting to stagnate:

Power consumption

You don't see any really dramatic differences in the Idle, although the Core i7-8700 is slightly above the K version. Nothing dramatic and all the other CPUs are still within the limits of what we were able to measure before. The fact that the Ryzen 7 sometimes absorb significantly more is probably also due to their somewhat too high idle time.

The average value of a typical application with 2D and 3D load components then coincides nicely with the actual measured performance values for the two new Intel CPUs.

In the gaming loop, both CPUs are then almost the same, which should have looked different on paper, but it is clear from the phenomenon that has been mentioned often enough that the Core i7-8700 often boosts at least as high as the core at lower loads. i7-8700K. The thing with the decimal point then almost tends towards measuring tolerance. And we also found that the Core i7-8700K very often has up to 0.1 volts more, although it did not always act faster than the Core i7-8700.

In the stress test with AVX you have the usual distance again, if you let the CPU on all cores drive the maximum turbo clock. Instead of the 110 watts when rendering without and plentiful 133 watts with overclocking to 5 GHz, AVX without offset lets the whole thing soar up to just under 170 watts, whereby the Core i7-8700K with 4.9 GHz already started to run into the thermal limit (package) – despite Chiller. Thanks to the loaus-like thermal paste.

Temperatures

The good news in advance: if you are not rendering for hours or playing Prime95, you would theoretically even come comfortably over the 4.8 GHz mark with a very good air cooler – assuming a well-ventilated housing. Here, the fun brake in the form of Intel's thermal paste is already limited, but it is possible.

The following curves show that an AiO can still keep the overclocked Core i7-8700K just below the first thermal limitations, despite fully inflated core voltage and after 20 minutes of warm-up time. A good air cooler should be able to do the same if you don't operate the computer in the summer-heated attic.

Under full load, it will then become scarce despite Chiller for the overclocked CPU. Even though we were only able to measure about 170 watts in the average, the partial throttling prevents the peaks with up to well over 180 watts from being consistently attached. At this point, the most potent water cooling fails.

Intermediate conclusion

It's amazing what they can swallow a small CPU if you just provoke them properly. Nevertheless, the Core i7-8700 and 8700K are relatively easy to cool, even with air. This works really well with the Core i7-8700K even when overclocked, as long as you don't render for hours or even use AVX-based applications. Then you should already think about at least an AiO water cooling.

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