01-04-2017, 07:35 AM
http://www.tomshardware.com/reviews/inte...70-12.html
Quote:We already mentioned that we used retail CPUs for all of our tests. This means that our results should be representative of what you can expect when you purchase a new Kaby Lake-based processor. In light of our experiences, early adopters should be aware that CPU quality can vary widely, and this is especially true for early production runs. We experienced this very problem with our Core i7-7700K retail sample.
It turns out that MSI has assessed 30 more retail Core i7-7700Ks. For each of them, the company found the minimum voltage necessary for stable operation under a given workload at a specific frequency. Thirty CPUs might not be a huge number, but it still yields a good idea of how much individual samples vary in quality.
The curve tells us that the Core i7-7700K in our German lab falls toward the bottom of the distribution. Both the voltages and the maximum frequency of “only” 5 GHz are the same as the ones on the bottom of the curve. This explains why that particular processor didn’t do so well under Intel’s Power Thermal Utility: its quality is just too low, necessitating a voltage increase that’s too high to allow for sufficient cooling.
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Alright, so Germany’s lab has two sub-par Core i7-7700Ks, and that's the hardware used in our performance, power consumption, and temperature benchmarks. However, the U.S. lab does have its own retail sample that consumes significantly less power. It also runs cooler.
We weren’t able to run all of our measurements in Germany and the U.S. with identical air coolers, so we went with compact closed-loop liquid coolers instead. Unfortunately, we still weren't able to achieve completely comparable performance. The Corsair H100i v2 in our U.S. lab gave us sporadic issues and generally didn’t cool as well. Consequently, we're only comparing power consumption results. We should still get plenty of information from those data points, though.
Whether we look at idle power consumption or the readings under Intel's Power Thermal Utility, the difference between samples is massive. And remember, these are retail processor we're comparing, not CPUs hand-selected by Intel for the press.
The difference between the CPU package and readings from the IA cores shrinks to a mere 2W. And leakage currents at the CPU’s highest temperature compared to before it warms up rise by a maximum of 1W. Compared to the four other CPU samples that we tested, this one’s really something special.
In this case, higher voltages paired with lower power consumption must mean lower currents, which keep the CPU significantly cooler.Once again, the Kaby Lake generation will see enthusiasts receiving great CPUs, mediocre CPUs, and terrible CPUs that still managed to make it through quality control. For the time being, we’ll have to live with this, since the manufacturing process isn’t mature enough to produce consistent high-quality results. We haven’t seen extreme differences like these since the days of Intel’s first quad-core CPU, the Q6600.