Overclocking the CPU
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 perhaps even 5.2 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 5000 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. Obviously we enabled the XMP profile on the memory for dual-channel 3200 MHz.
We hit roughly 60 Degrees C on the package sensor. Due to the x50 multiplier we hardly have to add any extra voltage, that paid itself back in respect to the temps. Our processor was not stable enough above the 5.1 GHz range.
At 5000 MHz you'll achieve ~1187 CB, at defaults that was 1038 CB, that is a pretty nice gain.
The default prime run scores 179 seconds, this tweak is at 146 second and thus shaved off a proper 33 seconds.