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Overclocking

The Haswell generation doesn’t sport high overclocking potential. As we learned earlier, the peak frequencies you can achieve with overclocker-friendly Haswell-based Core i7 CPUs are considerably lower than with previous-generation CPUs. The main reason for that is that the new CPUs get hotter at high loads due to the integration of voltage regulator components without any attempt to ensure more efficient heat transfer. Like with the Ivy Bridge series, there is a rather mediocre thermal interface between the Haswell’s semiconductor die and heat-spreader. The fluxless soldering employed for Sandy Bridge LGA1155 CPUs is now only used to manufacture the expensive products for the LGA2011 platform. Thus, the typical overclocking result you can reach with a Core i7-4770K is 4.4 to 4.5 GHz with a high-performance air cooler. And the CPU cores get very hot, up to critical levels, even after a small increase in CPU voltage.

It is hard to cool overclocked Core i5 CPUs, too, so we can't expect them to perform much better than their senior cousins. We can hope for a tiny increase in their overclocking potential due to the lack of Hyper-Threading technology, which means lower temperatures at full load. Let’s check this out with a Core i5-4670K which has unlocked frequency multipliers.

After increasing the voltage to 1.25 volts, we overclocked our Core i5-4670K to 4.5 GHz.

Our CPU couldn't do any better. When we tried to increase its voltage above 1.25 volts, it would overheat. In fact, the CPU was dangerously hot even at 1.25 volts. And if we didn't change the voltage but raised the clock rate higher, the computer would crash during our stability tests.

Thus, the overclocker-friendly Haswell-based Core i5 is no better in terms of overclocking than its Core i7 cousin. You can hardly expect any quad-core Haswell-based CPU to overclock higher than 4.4 or 4.5 GHz unless you use some special cooling methods or replace the thermal interface between the CPU's die and heat-spreader.

By the way, apart from the Core i5-4670K, the new Core i5 processors cannot be overclocked at all. Core i5 series CPUs with Ivy Bridge and Sandy Bridge design allowed to increase their frequency multiplier above the standard level even if they didn't belong to the overclocker-friendly K-indexed breed. Intel permitted a 400MHz frequency boost for them in addition to what was offered by the Turbo Boost technology. Now this useful feature is missing in the Haswell-based Core i5, so you cannot set a frequency multiplier higher than the maximum permitted by Turbo Boost for the non-K models.

Moreover, you cannot change the base clock rate with the Core i5-4670, Core i5-4570 and Core i5-4430, either. Intel implemented additional PCIe/DMI frequency multipliers in the LGA1150 platform, so the base clock rate can be set not only at 100 MHz but also at 125 or 166 MHz. However, this is only possible with the Core i5-4670K and Core i7-4770K. If you've got a Core i5-4670, Core i5-4570 or Core i5-4430, you cannot overclock your CPU at all. The new Core i5 products are similar to the Core i3 series in this respect.

We can illustrate this with a couple of screenshots. Here is the main CPU settings page on a Gigabyte Z87X-UD3H mainboard if a Core i5-4670K is installed.

After we replace the CPU with a Core i5-4670, which has the same specs, we get fewer settings:

The options for increasing the CPU frequency multiplier above the standard level or for changing the base clock rate just vanish. So if you’ve got a non-overclocking Core i5 on your LGA1150 platform, you will only be able to overclock system memory and the integrated graphics core.

 
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