Test Configs:
The CPU was stressed with Prime95 26.6 (no AVX) with
8K in-place FFTs. All testing was done in an S4 Mini. The following images show how the coolers were mounted:
BIOS/UEFI Settings:
The
latest BIOS update is supposed to disable multicore enhancement by default but it still reverts to overclocking focused "Auto" settings once you enable XMP for your memory. As a result, the CPU will draw about 120W at 4.3GHz before power limiting and
throttling to 95W at 3.9-4.0GHz. When properly tuned, the CPU power drops to 86-88W and
maintains 4.3GHz under all-core load. The "Tuned" settings listed below simply force the processor back to stock behavior. The VCCIO/VCCSA voltages work fine for typical DDR4-3200 and can be adjusted for higher speed kits.
VRM Heatsinks:
Removing one or more of the VRM heatsinks improves airflow and reduces CPU temperature at the expense of warmer MOSFETs. Since no one will be overclocking much, or at all, in the S4 Mini, the MOSFETs should stay reasonably cool. You can buy some
small heatsinks if you want more peace of mind. Here are some thermal images of the bare VRM under Prime95 load:
Delidding:
Just like the 7700K, delidding is helpful and
pretty easy to do. I used the
Rockit 88 kit and liquid metal. There's no tiny resistors to worry about on this chip.
Thermal Paste:
I used Noctua NT-H1 for every test except the last. Thermal Grizzly Kryonaut reduced core temperature by 2-3°C but there's nothing wrong with the stuff Noctua includes with their coolers and it's easier to apply.
Conclusion:
Managing the 8700K in the S4 Mini is a lot like the 7700K and 6700K before it. Expect to spend some time getting temperatures under control by delidding, tuning, or modding. My guess is that the i7-8700 will also be difficult to cool, despite the claimed 65W TDP. Strongly consider the i5-8400 or Ryzen 5 1600 for an easier time. For cooling, like
@Josh | NFC has mentioned before, Noctua is still the best overall when considering mounting, compatibility, and price.
