Testbed and Methods
We performed all our tests on a testbed built out of the following components:
- Mainboard: ASUS Z97-A rev. 1.03 (LGA1150, Intel Z97, BIOS 1008)
- CPU: Intel Core i5-4670K CPU (3.6-3.8 GHz, 4 cores, Haswell, 22nm, 84 W, LGA1150)
- DDR3 SDRAM: 4x8GB G.SKILL TridentX F3-2133C9Q-32GTX (2133 MHz, 9-11-11-31-2N, 1.6 volts)
- Graphics card: Gigabyte GV-R797OC-3GD (AMD Radeon HD 7970, Tahiti, 28 nm, 1000/5500 MHz, 3072 MB of GDDR5 memory with 384-bit bus)
- Disk subsystem: Crucial m4 SSD (CT256M4SSD2, 256 GB, SATA 6 Gbit/s)
- Cooling system: Noctua NH-D14
- Thermal interface: ARCTIC MX-2
- PSU: Enhance EPS-1280GA (800 W)
- Computer case: Antec Skeleton
We used Microsoft Windows 8.1 Enterprise 64-bit (Microsoft Windows version 6.3 build 9600) with latest updates and the AMD Catalyst 14.4 drivers.
We will compare the ASUS Z97-A with the Z87-PLUS model from the same manufacturer. It is a midrange model we haven’t tested before and it has all the characteristic traits of an ASUS mainboard like the CPU frequency drop at high loads. We won’t see much difference comparing two similar mainboards but our goal is to check out the two chipsets, the new Intel Z97 and the old Z87. We’ll be comparing mainboards with the same chipset in our upcoming review.
We had no problems assembling our configuration with the ASUS Z97-A and updating the mainboard's firmware to the latest version. As is typical of all ASUS mainboards, the startup picture only mentions that you can press Del or F2 to enter the BIOS interface. ASUS persists in not telling us anything about the other active hotkeys. For example, you can press F8 to open a menu for choosing an out-of-order boot device but you can only learn about that from the user manual.
You can disable the startup picture with the Tab key (temporarily) or in the BIOS (permanently), but you won’t see any prompts, either. What you will see is information about the mainboard’s model name, BIOS version, CPU model, the amount and frequency of system memory, the number and type of USB devices, and the connected disks. The real CPU clock rate is not reported, though. The mainboard doesn’t count in any CPU overclocking you've done or any changes to the CPU frequency multiplier due to the Intel Turbo Boost technology. This downside is especially annoying as we know that ASUS’s ROG series products can correctly report both nominal and actual CPU clock rates.
Modern mainboards start up very fast and this may even present a problem for users of ASUS mainboards. It is only at the first launch that the mainboard lets you enter its BIOS. After that, the startup procedure gets so fast that you hardly have any time to hit the required key. The ASUS Z97-A lacks the DirectKey feature which would lead you right to the BIOS interface but has the so-called DirectKey Connector you can attach your computer case's Reset button to. DirectKey is not convenient, though. Instead of rebooting and entering the BIOS, it shuts the computer down first. Then you have to power it up again to find yourself in the BIOS. You can use the ASUS Boot Setting utility instead. Its functionality is okay, but you have to install it first. Moreover, it only runs under Microsoft Windows. So when you’re setting up your mainboard after purchasing it, you may want to disable the Fast Boot option in the Boot section, which is turned on by default.
The mainboard seems to provide standard conditions for the CPU by default but that's not really so. If you manually enable all of Intel’s power-saving technologies on the CPU Power Management Configuration page (in the CPU Configuration subsection of the Advanced section of the mainboard’s BIOS), you will make your computer substantially more economical.
You can also get some additional power savings by optimizing CPU Power Phase Control in the DIGI+ VRM page of the Ai Tweaker section. Then, you can also enable Power Decay Mode in the Internal CPU Power Management page and choose the balanced mode for the CPU Integrated VR Efficiency Management option.
Why don’t we just use the EPU Power Saving Mode? Well, we are rather wary of exclusive power-saving technologies because it is not clear what they actually do. They may supply lower voltage to the CPU or use lower CPU clock rates. The difference is going to be felt at high loads. For example, the EPU feature helped reduce the computer's power draw from 118 to 110 watts while running LinX. The idle power consumption didn’t change, though. It was still rather high at 42 watts. Our manual adjustment keeps the CPU working at its standard settings and doesn't affect its performance. We simply enable each and every power-saving feature the CPU already has. They are just not enabled by default. As a result, the idle power consumption goes down from 42 to 38 watts. So that’s what you should do first. And after you make your CPU as economical as possible, you may want to reduce your computer's power draw even more (although perhaps at the expense of performance) by applying any exclusive power-saving technologies from the mainboard maker.
As a matter of fact, all LGA1150 mainboards we've seen so far do not enable all of the CPU-related power-saving features by default. But ASUS products have one more downside. They are going to drop the CPU frequency multiplier to the base level at high loads although it should be higher due to the Intel Turbo Boost technology. To avoid this frequency drop, you should increase the CPU power targets in the mainboard's BIOS (Ai Tweaker -> Internal CPU Power Management).
Interestingly, you don’t have to specify those power targets yourself when you overclock. The mainboard will automatically increase them to ensure that the CPU frequency multiplier is as high as necessary. That’s why it is odd that the mainboard doesn’t do so at the default settings. Anyway, this problem only occurs at very high loads. It is unlikely to arise in everyday applications or games.