Now it’s getting exciting, because depending on the CPU or APU (CPU with integrated graphics chip) and depending on the motherboard whether and how we can change the multiplier of the processor.
When an Intel LGA1150 CPU is used, there are three ways in fact:
- We use an unlocked CPU (K/C), with free selectable multiplier (E.g. Intel Core i7-4790K, Intel Core i5-4690K, Intel Core i7-5775C and the Intel Pentium G3258 Anniversary Edition, etc. is also unlocked). We can increase the multiplier easily via the UEFI Setup or by a OC Software – this is the best requirement for overclocking the processor. The standard multi of an Intel Core i5-4690K is for example 35x and the Turbo Core has 39x BCLK. With ASRock motherboards you set up CPU Ratio from Auto to All Core (overclock all cores at the same time), then increase the multiplier over this All Core value. ASUS calls it the Ai Tweaker menu and when you set Ai Overclock Tuner to Enabled, you get the multiplier option to increase the Cores from 8x to 120x (of course we do not reach 120x, because this would result in 12000 MHz). Intel Turbo Boost Technology – short Turbo should be disabled for the first OC attempts.
- We use a Non-K CPU with locked multiplier but with Turbo function (E.g. Intel Core i7-4790, Intel Core i5-4460, Core i5-4690, etc.). Here we can’t increase the multiplier over the BIOS or UEFI Setup, but Intel allows a reduction of the CPU multiplier. The base multiplier at an Intel Core i7-4790 CPU is 36x BCLK and the Turbo goes at least to 40x BCLK. We can take advantage of this Turbo to overclock the CPU. However, the maximum Turbo value will be adjusted depending on the CPU Core load.
- We use a Non-K CPU with locked multiplier without Turbo function (E.g. Intel Core i3-4170, Core i3-4150, Core i3-4130, Celeron G1840, Intel Pentium G3220, Pentium G3450, etc.). Here we can not increase the multiplier over the BIOS or UEFI Setup, because Intel allows only a reduction of the CPU multiplier. The base multiplier of an Intel Core i3-4170 CPU is 37x BCLK and remains because there is no Turbo. For Core i3 and other multi locked processors without Turbo remains only the overclocking using the BCLK which we explain in the next step.
Now we know whether and in which range the multiplier can be changed, but before we overclock using the multiplier, it continues now with the determination of the highest FSB / BCLK.
Determine the highest BCLK …