Intel Core i7 8700K processor review

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BIOS overclocking

Overclocking and tweaking then. Always invest in good hardware by the way (MOBO/PSU/Memory/Cooling), the cheaper motherboards often are not well tuned or have broad-spectrum features for enthusiast overclocking. Also get yourself a good power supply and proper processor cooling. Overclocking with a many core processor (doesn't matter if that is Intel or AMD) is more complicated than you expect it to be.  Overclocking multi-core on a high clock frequency is a relatively easy to do job, but is managed best from the BIOS. The Guru3D reader-base overclocks mostly from the BIOS to try and find the maximum stable limit. The generic overclock procedure for multiplier based overclocking is as follows:

Your reachable target for Coffee Lake is 5 GHz and 5.2 maybe even 5.3 GHz with a really good processor.

  • Leave base clock (bus) for what it is right now (100 MHz)
  • Set the per core multiplier at a maximum of your liking:
  • Example 1: 100MHz x 50 = 5000 MHz
  • Example 2: 125MHz x 40 = 5000 MHz
  • Increase CPU voltage; though AUTO often works fine on many motherboards you can do it manually as well. Start at 1.35 ~ 1.40 volts and work your way upwards into a state of equilibrium in perf and cooling temps.
  • Make sure your processor is properly cooled as adding voltage = more heat
  • Save and Exit BIOS / uEFI



In our case we got all cores running at 5200 MHz, however this results in extra power consumption and heat levels. Our Corsair LCS cooler was barely capable of cooling the proc enough as shown below, roughly 1.385~1.400 Volts is needed and obviously we enabled the XMP profile on the memory for dual-channel 3200 MHz. 


We hit 88~90 Degrees C on the package sensor. However to be fair, we have been able to sustain a stable 5.2 GHz on all cores. Memory wise we have 3200 MHz stable (dual channel).

Power Consumption

Adding extra voltage on the CPU for the OC also has an adverse effect on the overall energy consumption. Under stress and overclocked we all of a sudden use roughly 380 Watt under full processor load (!). That is power consumption for the whole PC measured at the wall socket side including a GeForce GTX 1080 in idle. Overclocked in idle your system will use roughly 10 to 15 Watts more on average.





Overclocking will differ per processor and motherboard. We'll look deeper into processor overclocking with the Z370 motherboard reviews. 

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