Operational and Overclocking Specifics
We had no problems assembling our testbed around the Gigabyte GA-Z87X-D3H mainboard. It started up successfully, showing us the familiar picture with information about active hotkeys. You can enter the BIOS interface by pressing the Del key. The F9 key will open up a system info window, the same as you get when you press the same key in the BIOS. F12 shows a list of devices you can boot from. The End key launches the integrated BIOS update tool Q-Flash.
You can turn off the startup picture but there is no point in doing this. As opposed to mainboards from most other brands, Gigabyte ones do not report any useful information about the CPU or memory during the startup process. Again, you can only read some basic system info by pressing F9 during the startup procedure or in the BIOS interface.
In its default mode the mainboard set standard settings for the CPU and memory. However, just like with the ASUS Z87-K, you can lower its power consumption considerably if you switch all power-saving technologies in the BIOS’s Advanced CPU Core Features page from Auto to Enable. We’ll see that in our power consumption tests shortly.
Using the integrated graphics core of an Ivy Bridge CPU in our review of the ASUS P8Z77-M and Gigabyte GA-Z77M-D3H, we noticed that the Gigabyte mainboard would set its clock rate higher by 50 MHz. The Gigabyte GA-Z87X-D3H turns out to do the same with the Haswell processor, making the integrated graphics core of our Intel Core i5-4670K work at 1250 MHz instead of the standard 1200 MHz. It is not a big deal, yet we have to mention this deviation from the standard operation mode.
Gigabyte’s new UEFI DualBIOS brings us long-anticipated automatic overclocking features. Earlier, they could only be accessed via the Windows-based Easy Tune utility. So now you can find the CPU Upgrade option on the Frequency tab of the Performance section in the BIOS interface. When you choose it, a dropdown menu opens up, offering you to select the desired CPU clock rate. The rest of settings required for overclocking will be applied automatically. The Performance Boost option works in the same way but overclocks system memory along with the CPU. Oddly enough, the mainboard didn’t use the XMP profile of our memory modules for that but simply increased their frequency from 1333 to 1600 MHz. Well, some memory modules may just lack XMP profiles, so the small increase in frequency above the standard level is a universal overclocking method that suits any memory. Besides that, the Memory tab of the Performance section offers the rather rare option called Memory Upgrade which helps increase memory frequency in case that your modules lack XMP profiles.
The biggest problem about the mainboard’s automatic overclocking features (CPU Upgrade and Performance Boost) is the way it increases CPU voltage. The mainboard does that in the offset mode, adding a certain value to the standard one. It would be perfect with an LGA1155 processor of the Sandy Bridge or Ivy Bridge series since this method keeps Intel’s power-saving technologies up and running, resulting in energy efficient overclocking. But it doesn’t work for LGA1150 Haswell processors because their integrated regulator increases the voltage suddenly at high loads, provoking overheat. We had the same problem with the ASUS Z87-K when we selected the Ratio Only method of the automatic overclocking feature OC Tuner. We guess both these features should be removed from the BIOSes of both mainboards or at least substantially revised because in their current way they are no good at all or even harmful.
For example, using the CPU Upgrade and Performance Boost features, we selected parameters that would increase the CPU clock rate on the Gigabyte GA-Z87X-D3H to 4.3 GHz, which isn’t very high. In this case, the CPU voltage was rather high at 1.275 volts in ordinary applications. And when we launched the resource-consuming LinX utility, the voltage got critically high – over 1.3 volts. Such overclocking is no good even if the protection system prevents any damage to the mainboard or CPU by shutting them down: the overheat triggers CPU throttling which lowers performance instead of increasing it.
Well, Gigabyte’s new UEFI DualBIOS offers one more automatic overclocking feature that works in a rather unexpected way. It is the K OC option you can find on the Advanced CPU Core Features page of the Performance section. Judging by its name, it is meant for overclocking K-indexes CPUs which have unlocked frequency multipliers. When enabled, this feature stepped up the multipliers of our Intel Core i5-4670K by x2. In other words, the Intel Turbo Boost technology now increased the clock rate to 3.8 rather than to 3.6 GHz at full load. When three CPU cores were in use, the clock rate was 3.9 instead of 3.7 GHz. The peak clock rate was 4.0 GHz when only one or two CPU cores were in use. There’s nothing special about this overclocking method. For example, ASUS mainboards can use a single frequency multiplier for all CPU cores but you can specify individual multipliers for each core, so the resulting frequency is going to depend on how many CPU cores are in use. The interesting thing about the Gigabyte method is that the CPU voltage was only increased to 1.130 volts with such overclocking. That’s not much, so this overclocking method can be recommended for use.
How is it possible, though? After our tests of the ASUS Z87-K mainboard, we know that the Haswell’s integrated voltage regulator will always increase voltage to an unacceptably high level at overclocking. Energy efficient overclocking is not possible in that case, so we have to compromise. If we increase CPU voltage in the offset or adaptive mode, the integrated regulator will set it too high, wasting energy and triggering CPU throttling due to overheat. That’s why we fixed the voltage at a certain level for our overclocking tests with the Z87-K. In this case, power-saving technologies lower the CPU frequency multiplier at low loads but do not reduce its voltage. We found out, however, that the constant voltage didn’t affect the computer’s power draw at low loads. It was not increased too much at high loads, either. That’s why we recommended to overclock Haswell CPUs using fixed voltage.
Gigabyte’s mainboards are different as they support energy-efficient overclocking of Haswell CPUs. You just don’t have to increase any voltages at all, setting the CPU Vcore and CPU Vcore Offset options at Normal. In this case, the voltages will be increased a little due to certain correlation between CPU voltage and frequency. Both are low and constant when there is no load. As the load and frequency go up, the voltage is increased to ensure stability. The voltage reaches its maximum when the CPU works at its highest frequency thanks to the Intel Turbo Boost technology. This is the generic rule of behavior for any mainboard when the CPU is not overclocked. However, Gigabyte mainboards turn out to support overclocking in this way. The small increase in voltage due to the increased top limit for the CPU frequency multiplier even helps ensure stability at higher frequencies. We ran some tests immediately and made sure that the CPU could be overclocked to 4.3 GHz without increasing its voltage, which is a very good result for a Haswell.
At high loads the voltage was higher than when the Core i5-4670K worked at the default settings, just because its clock rate was higher. We didn’t tweak the voltage at all. The mainboard didn’t do that, either. The CPU-integrated regulator behaved normally and didn’t try to step the voltage up beyond reasonable limits. The voltage of 1.134 volts is roughly the value that we would have at the default settings if there existed a CPU whose top frequency (with Intel Turbo Boost) were 4.3 GHz. Intel’s Haswell series doesn’t include such models, but the energy efficient overclocking of the Gigabyte mainboard produces one. This overclocking method is perfect for LGA1150 processors because performance grows up considerably thanks to the higher clock rate but the voltage isn’t high at high loads and drops to the same low level at low loads as at the default settings.
The CPU’s power-saving technologies stay enabled, so you don’t have to compromise as when you overclock with volt-modding. Unfortunately, you need a Gigabyte mainboard for this overclocking method. We already know that ASUS mainboards don’t support it and are yet to check out other brands’ products. The problem with ASUS mainboards is that they can only supply standard voltage when the CPU works at the default settings. If you change the CPU Core Voltage option at Auto, the too smart mainboard will increase CPU voltage automatically, although we don’t really need that. We used to increase it by the minimum value of 0.001 volts to avoid that. This is too little to affect the behavior of any CPUs, except for LGA1150 ones. The integrated voltage regulator of Haswell CPUs is going to spot even such a small increase in voltage and raise it additionally at high loads. Thus, the voltage is increased in either case, by the mainboard or by the CPU-integrated regulator. That’s why it’s impossible to overclock Haswell CPUs on ASUS mainboards without volt-modding as on Gigabyte ones.
Anyway, even though we do recommend to overclock LGA1150 without volt-modding, we sped up our test sample to its maximum 4.5 GHz after fixing its voltage at 1.150 volts. We also used the XMP settings for our memory modules.
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 called CPU Overclocking vs. Power Consumption. 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.
When the CPU voltage is fixed at a certain level, some power-saving technologies stop to work, so the voltage isn’t reduced at low loads. We have to put up with that for the time of our tests, especially as it doesn’t affect the computer’s idle power draw much. We’ll talk about power consumption shortly, though. Right now, let’s see what performance benefits can be expected from overclocking.