We carried out our tests on a testbed that included the following components:
- Asus Sabertooth Z77 mainboard (LGA 1155, Intel Z77 Express, BIOS version 1206);
- Intel Core i5-3570K CPU (3.6-3.8 GHz, 4 cores, Ivy Bridge rev.E1, 22nm, 77 W, 1.05 V, LGA 1155);
- 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;
- CoolerMaster RealPower M850 PSU (RS-850-ESBA);
- Open testbed built using Antec Skeleton system case.
We used Microsoft Windows 7 Ultimate SP1 64 bit (Microsoft Windows, Version 6.1, Build 7601: Service Pack 1) operating system, Intel Chipset Software Installation Utility version 188.8.131.520, AMD Catalyst 12.4 graphics card driver.
Operational and Overclocking Specifics
When we assembled our Asus Sabertooth Z77 based system we didn’t have any problems or difficulties. Although I have to admit that I immediately disconnected the fan for cooling the heatsinks on the processor voltage regulator components. This small 35 mm fan rotates too fast even though the rotation speed adjustment is in place. The heatsinks it cools do not heat up even under heavy load and during CPU overclocking, so there was no need to put up with additional noise.
During system startup you will see a startup image, where there was no mention of any hot keys besides “Del”.
Disabling the startup image won’t pay off big. The board can’t tell us the actual CPU clock frequency, and will always report the nominal one. The hints about available hot keys also won’t come up on the screen.
Besides the extra noise from the 35 mm fans, there are no other comments on our part about the mainboard operation in nominal mode. Automatic system overclocking using “OC Tuner” parameter in the mainboard BIOS also was a success, and even though we weren’t at all disappointed with the obtained results, we weren’t super-excited either. The CPU clock speed rose to 4.22 GHz, all power-saving technologies remained up and running flawlessly, but the memory frequency didn’t change at all.
As for the manual overclocking, we faced some unexpected difficulties trying to keep the system stable at 4.6 GHz as well as 4.5 GHz CPU clock.
Here it is important to remind you that our particular processor is overclocked to 4.6 GHz frequency only when we reviewed the first three mainboards on Intel Z77 Express chipset: Asus P8Z77-V Deluxe, ASRock Z77 Extreme4 and ASRock Z77 Extreme6. All mainboards tested after that, namely, Gigabyte G1.Sniper 3, MSI Z77A-GD65, Intel DZ77GA-70K and Intel DZ77RE-75K stopped at 4.5 GHz. We should strike out the MSI board, because we intentionally didn’t raise the CPU core voltage when we overclocked on it in order to keep processor power-saving technologies intact. However, if we add here the results obtained with the Asus Sabertooth Z77 board, we can clearly suspect that our processor could have degraded substantially. With the first three mainboards we even attempted to hit 4.7 GHz, but decided to stop at 4.6 GHz because of extremely high temperatures. The second group of mainboards managed to overclock this processor to 4.5 GHz, and now we can’t get even that, although we were optimistic that Asus Sabertooth Z77 would push the overclocking results back to 4.6 GHz.
However, before we make bold statements like that, let’s take a closer look at this situation. At first we ran all tests in the nominal mode and everything went flawlessly. After that we increased the memory frequency and again didn’t have any problems. It indicates that the experienced issues have nothing to do with the actual benchmarks or operating system and are not connected with the memory overclocking. They emerge only when we attempt to overclock our CPU. Therefore, we assembled a testbed using ASRock Z77 Extreme4 mainboard – one of the boards that managed to previously overclock our processor to 4.6 GHz. Of course, the testing conditions were not fully identical to what we had before, because since then new drivers and BIOS versions came out. However, the new BIOS version didn’t prevent ASRock mainboard from passing all stability tests with flying colors at the same 4.6 GHz CPU clock.
In other words, there is no sign of any CPU degradation. It is still capable of hitting higher numbers and if we can’t do that, the CPU is not the one to blame. Since we couldn’t get Asus Sabertooth Z77 to overclock our processor beyond 4.4 GHz we had to stop at this CPU frequency and 1867 MHz memory frequency. This overclocking didn’t require any Vcore increase; all we had to do was to enable minimal CPU Load-Line Calibration.
Now I would only like to remind you that we always overclock mainboards in such a way that they could be used for a prolonged period of time in this mode. We do not try to make our life easier by disabling any of the mainboard features, such as onboard controllers, for example. We also try to keep the CPU's power-saving technologies up and running normally to the best of our ability. And this time all power-saving technologies remained up and running even during overclocking lowering the CPU voltage and frequency multiplier in idle mode.