The ASUS Z97-A behaves like Z87-based products from the same brand at its default settings but there are some differences when it comes to overclocking. There’s the new EZ Tuning Wizard that’s supposed to help you overclock your computer and build a RAID. The latter feature may be easily overlooked, so we guess it should have been separated.
First off, the wizard identified that the CPU and memory worked at their default settings.
Then it inquired what the computer’s intended applications were. Of course, we answered that we wanted to play games and transcode video.
Then we were asked to choose the type of the CPU cooler. There’s a special answer for those who’ve purchased a ready-made computer and don’t know the details, but we use a tower-design Noctua NH-D14.
By the way, the Noctua NH-D14 has two 3-pin fans and none of the Socket FM2+ mainboards (based on the AMD A88X chipset) we tested, including an ASUS model, could regulate those fans, so they always rotated at their maximum speed. The ASUS Z97-A, on the contrary, provides full comfort by adjusting the speed of the fans depending on CPU load and temperature.
The wizard had no more questions to ask. It promised to boost CPU and memory performance but warned us that we should load the default settings in case of unstable operation.
This warning is necessary indeed as we realized after the computer had been rebooted.
The wizard raised the base clock rate a little, increased the CPU frequency multiplier to x44 and overclocked system memory using relaxed timings. Everything is okay so far, but the CPU voltage is going to be as high as 1.25 volts at high loads, which is too much. When the load is high and continuous, the CPU overheats, then drops its clock rate and speed. So, this overclocking is useless. The EZ Tuning Wizard algorithms need more optimizing. We don’t recommend using this feature until then.
Like with other ASUS mainboards, you can enable the ASUS MultiCore Enhancement option to increase the CPU frequency multiplier to its maximum level, which is normally used by Intel Turbo Boost for single-threaded loads only. It is set at Auto by default and doesn’t work. To enable it, you should do some overclocking, like changing your memory subsystem parameters with an XMP profile. For more substantial overclocking, the OC Tuner feature or the onboard TPU switch should be used. If you choose Ratio Only, the computer is overclocked by increasing the CPU frequency multiplier.
Of course, the result is lower than with EZ Tuning Wizard, but it will work even for high continuous loads. Interestingly, the OC Tuner feature used to adjust CPU parameters only but now it applies the XMP profile to speed up system memory, too.
And if you choose BCLK First, the OC Tuner feature will increase the base clock rate as well.
The resulting CPU clock rate is higher but the memory frequency is lower. The CPU voltage is higher in this case, too. But whatever OC Tuner method you choose, automatic overclocking is always imperfect, on any mainboard. You will get much better results by finding optimal system parameters manually. You will either reach higher clock rates or make your computer more efficient in terms of power consumption and heat dissipation.
The best way to overclock is without increasing voltage, but it is impossible to just set the CPU frequency multiplier higher and leave the rest of the settings intact. In this case, the mainboard will automatically increase the CPU voltage, and the CPU-integrated regulator will increase that voltage even higher at high loads. That is likely to end in overheat and, in any case, that's no energy-efficient overclocking at all. To avoid this, you have to change CPU Core Voltage to Manual. In this case, the mainboard and the integrated regulator don’t increase the voltage anymore.
You may also want to disable CPU Load-Line Calibration and Internal PLL Overvoltage, which may only be necessary for extreme overclocking.
Energy efficient overclocking is only possible if you don’t increase voltage. It will ensure higher performance and, despite the increased power consumption, you can expect long-term savings due to the reduced amount of energy spent for each computation. Energy efficient overclocking is going to be environment-friendly as we showed in our Power Consumption of Overclocked CPUs review. However, when we test mainboards, we want to check them out under different conditions and loads, so we choose what overclocking method ensures the highest results. Higher clock rates and voltages mean harsher test conditions and it is under such conditions that we can better see any flaws or problems in mainboard design.
We used to increase voltage in the offset mode and the LGA1150 CPUs also support a similar adaptive mode, but such methods do not work well with Haswell-based CPUs. The fact is as soon as the default voltage is changed even by a tiny value, the Haswell’s integrated regulator will spot it and increase the voltage further at high loads, which means high heat dissipation, high temperature and, eventually, overheat. To avoid this, the Haswell must be overclocked at a constant voltage. The downside is that the CPU’s power-saving technologies cease to work: the CPU frequency multiplier drops at low loads but the voltage doesn’t drop anymore and always remains at the constant and high level. This is the only way to deal with the integrated voltage regulator, though. Moreover, it doesn’t affect the computer’s power draw in idle mode. That’s why we overclock our CPU to 4.5 GHz in our mainboard reviews, fixing the voltage at 1.150 volts and using the XMP settings for our memory modules.
When we overclock by fixing the CPU voltage at a certain level, some of the power-saving technologies get disabled. The CPU's frequency multiplier is lowered at low loads but its voltage always remains high. Anyway, we stick to this overclocking for the duration of our tests, especially as it doesn't affect the computer's idle power draw much.
By the way, earlier we published an article called Haswell and LGA 1150 Platform: Right Operation and Overclocking where we explained the basic rules for optimizing LGA1150 platform parameters and for overclocking Haswell-based CPUs on mainboards from different brands. There you will find our illustrated recommendations on enabling Intel’s power-saving technologies and increasing CPU power targets as well as on how to overclock Haswell-based CPUs with and without voltage adjustment.