Clock Frequencies

The following chart shows how well the processor sustains its clock frequency, and which boost clock speeds are achieved at various thread counts. This test uses a custom-coded application that mimics real-life performance—it is not a stress test like Prime95. Modern processors change their clocking behavior depending on the type of load, which is why we provide three plots with classic floating point math, SSE SIMD code, and the modern AVX vector instructions. Each of the three test runs calculates the same result using the same algorithm, just with a different CPU instruction set.

Overclocking

The Core i5-12600 has its multiplier locked (no "K" suffix). You can technically overclock the base clock (BCLK) to 102.9 MHz, but that will only give you around 3% performance gains at best. Increasing BCLK beyond that limit isn't possible because Intel includes a BCLK counter in their CPU, which will shut off the CPU at 103 MHz and above.

That rule doesn't apply to motherboards that come with an external clock generator. Normally, all Alder Lake CPUs generate BCLK internally, with the 103 MHz limitation active. For hardcore overclocking purposes, Intel also included a way to feed an external clock signal to the CPU, bypassing the internal clock generator. Turns out the 103 MHz limit doesn't apply to BCLK provided by an external source.

Unfortunately, this capability is only available on a few Z690 motherboards from ASUS, but given the results we're seeing here, I'm quite positive that all motherboard vendors are looking into bringing this capability to their whole lineup, possibly on cheaper B660 motherboards, too. On the other hand, I'm just as sure Intel is looking into methods to block this capability through BIOS updates.

With BCLK overclocking, things are a bit more complicated than with multiplier overclocking. While the multiplier will only affect the CPU's operating frequency, BCLK is also fed into the memory controller, so raising the BCLK will also overclock the memory. It might also affect other things, like PCIe speed, but all motherboards with BCLK overclocking support also support setting these secondary clocks to a fixed value. As an example, in order to keep the memory at the original frequency when overclocking the BCLK by 20%, you would pick a 20% lower memory setting in BIOS. Due to the multipliers not supporting fractions, the values here will often not line up perfectly. In my case, I was lucky I could use 125 MHz BCLK, which combined well with a x40 multiplier to achieve 5.0 GHz and DDR5-6000. If you end up with a small memory speed mismatch, don't worry, the differences are negligible.

A little trick to make your BCLK overclocking progress easier is to first downclock the CPU via the multiplier in BIOS—even non-K CPUs can lower their multiplier, just not increase it. I started with a BCLK of 125 MHz and a multiplier of x20 to boot into Windows with a perfectly safe and stable 2.5 GHz. I then fired up a Prime95 stability test and at the same time slowly increased the multiplier with ThrottleStop until the system crashed. This happened at x41 (5.125 GHz).

You can now fine-tune the overclock by changing the BCLK and playing with the multiplier. You can only go in full BCLK steps. So BCLK 125 x24 = 3.0 GHz, and the next step is x25 = 3.125 GHz. If you want 3.1 GHz, you'll have to find a BCLK + multiplier combination that gives you that target while keeping the memory within your targeted range.

My maximum overclock turned out to be almost 5.0 GHz. Most tests were stable at that frequency; except for heavy loads like rendering. I tried increasing the voltage, for which there is plenty of headroom because the processor runs quite cool, but even +0.2 V didn't achieve full stability. That's why I settled for 4.9 GHz, which allowed me to run at very low voltage, which helped with energy efficiency and temperatures.