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

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Core i7-8700K Coffee Lake Overclocking

Overclocking the Intel Core i7-8700K Coffee Lake processor on the Gigabyte Z370 AORUS Gaming 7 motherboard ($249.99) with BIOS Version F4a is super simple and the Graphical User Interface (GUI) was easy to navigate and find what you needed to get to. There were a few minor issues we found on this early pre-public UEFI build and hopefully they’ll get them patched up on the next release version.

5100MHz Cinebench

We overclocked our Intel Core i7-8700K Processor up to 5.1 GHz by just raising the multiplier in the UEFI and changing no other settings. In just seconds we were running on the desktop and able to benchmark at 5.1 GHz with full stability.

5200MHz Cinebench

We pushed on and was able to hit 5.2 GHz by increased the multiplier up to 52x and changing nothing else in the UEFI. We could still run some benchmarks, but we wouldn’t call the system fully stable.

8700k 5300mhz

Just for fun we wanted to see if we could get into Windows and run any benchmarks at 5300MHz and we were amazed that we could get 5.3 GHz to boot and we were on the desktop at those clock speeds. It wasn’t stable enough to run Cinebench, but it was running!

After hitting 5.3 GHz and having some fun we got serious and started to monitor the temperatures closely to see if we were thermally throttling. The Corsair Hydro Series H105 water cooler ($114.99) is a pretty decent with its extra-thick 240mm radiator and dual SP120L fans, but we noticed that we were getting up over 95C on the individual cores. The Intel Core i7-8700K idles at a super cool 23-26C per core and then when the cores start running at 5,100 MHz they instantly jump up to around 90C, so good cooling is going to be needed for overclocking.

When we were running the AIDA64 stress test we noticed that the Package TDP hit 133 Watts (stock we only hit 75 Watts) and we did see on the Intel Extreme Tuning Utility (XTU) that the 8700K was thermal throttling. The good news is that despite XTU flickering the Thermal Throttling notice the clock speed and core voltage didn’t show that they were dropping. Due to temperature concerns we were more than happy with our 5.1 GHz overclock on the Core i7-8700K and it was solid enough to run every benchmark in our test suite at those speeds. That means we’ll be including benchmark results on the 8700K at stock speeds and all cores at 5.1GHz for this review!

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