We performed all our tests on a testbed built with the following components:
- Mainboard: Asus Z87-K rev.1.03 (LGA 1150, Intel Z87, BIOS version 0309);
- Intel Core i7-4770K CPU (3.7-3.9 GHz, 4 cores, 8 threads, Haswell, 22nm, 84 W, LGA 1150);
- 2 x 4 GB DDR3 SDRAM Corsair Vengeance CMZ16GX3M4X1866C9R (1866 MHz, 9-10-9-27 timings, 1.5 V voltage);
- Gigabyte GV-T797OC-3GD (AMD Radeon HD 7970, Tahiti, 28 nm, 1000/5500 MHz, 384-bit GDDR5 3072 MB);
- Crucial m4 SSD (CT256M4SSD2, 256 GB, SATA 6 Gbps);
- Scythe Mugen 3 Revision B (SCMG-3100) CPU cooler;
- ARCTIC MX-2 thermal interface;
- Enhance EPS-1280GA 800 W PSU;
- Open testbed built using Antec Skeleton system case.
We used Microsoft Windows 8 Enterprise 64 bit (Microsoft Windows, Version 6.2, Build 9200) operating system, Intel Chipset Device Software drivers version 220.127.116.117, AMD Catalyst graphics card driver version 13.4.
Operational and Overclocking Specifics
We got down to studying the new platform following our long-established procedures. We had no problems assembling our testbed configuration with the ASUS Z87-K. When we started it up, we saw the familiar startup image which is rather uninformative. It only mentions the well-known Del key you can press to enter the BIOS interface, but ASUS persists in not telling us anything about the other active hotkeys. For example, you can press Tab to remove the picture whereas F8 will open a menu for choosing the device to boot from.
There are no changes in the information the mainboard outputs while passing the startup procedure. You can see its model name, BIOS version, CPU model, the amount and frequency of system memory, the number and type of USB devices, and a list of 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.
Well, today’s mainboards start up so fast that you can barely have enough time to punch the button to enter their BIOS, let alone read anything from the screen. So, in order to load the BIOS interface automatically, you can use the ASUS Boot Setting utility available for Microsoft Windows. When you’re setting up your mainboard for the first time, you may even want to disable the Fast Boot option in its BIOS (it is enabled by default) to have no problems accessing the BIOS interface.
We have one concern about the mainboard’s behavior at its default settings. Not all of the power-saving technologies implemented in Intel CPUs are turned on by default. You have to enable them manually. Most of the power-saving options you can see in the BIOS are set at Auto when you first start the mainboard up, but when you change them to Enabled, the mainboard’s power consumption lowers considerably. Thus, the Z87-K consumes much more power than necessary at the default settings. We’ll see this in our power draw tests shortly.
When all the cores of the Intel Core i7-4770K processor are in use, its clock rate should be 3.7 GHz. If three cores are used, the clock rate is increased to 3.8 GHz. And if only one or two cores are used, the clock rate may grow up to 3.9 GHz. However, we found the CPU frequency multiplier to drop to its default level in AVX-using applications, so the clock rate might get as low as 3.5 GHz. This effect didn’t depend on how high the load was. It might even be a single-threaded application. Supposing that the problem might be due to the Intel Turbo Boost technology, we tried to increase the permissible power consumption levels of the CPU but to no effect. Then, we observed no such frequency drops while overclocking our CPU. And what do we do at CPU overclocking besides changing voltages? We manually specify the frequency multipliers. So, we also specified them manually for the standard operation mode, and such frequency drops discontinued.
This problem has no relevance for ordinary applications because the clock rates remain standard. The performance hit in AVX-using applications isn't large, either, yet we hope that it will be eliminated in upcoming BIOS updates.