Testbed and Methods
All performance tests were run on the following test platform:
- Asus Sabertooth X58 rev. 1.02 mainboard (LGA1366, Intel X58 Express, BIOS version 0603);
- Intel Core i7-930 CPU (2.8 GHz, Bloomfield D0);
- 3 x 1024 MB Kingston HyperX DDR3-1866, KHX14900D3T1K3/3GX, (1866 MHz, 9-9-9-27 timings, 1.65 V voltage);
- HIS HD 5850, H585F1GDG graphics card (ATI Radeon HD 5850, Cypress, 40 nm, 725/4000 MHz, 256-bit GDDR5 1024 MB);
- Kingston SSD Now V+ Series (SNVP325-S2, 128 GB);
- DVD±RW Sony NEC Optiarc AD-7173A optical drive;
- Scythe Mugen 2 Revision B (SCMG-2100) CPU cooler;
- Zalman CSL 850 thermal interface;
- CoolerMaster RealPower M850 PSU (RS-850-ESBA);
- Open testbed built using Antec Skeleton system case.
We used Microsoft Windows 7 Ultimate 64 bit (Microsoft Windows, Version 6.1, Build 7600) operating system, Intel Chipset Software Installation Utility version 126.96.36.1995, ATI Catalyst 10.9 graphics card driver.
Operational and Overclocking Specifics
We had no problems running our Sabertooth X58 in its default mode. We easily assembled our testbed around it and installed the OS. The CPU would lower its frequency and voltage in idle mode.
To make the most of the power-saving modes and Intel Turbo Boost technology we enabled the Intel C-STATE Tech option in the mainboard’s BIOS. As a result, the CPU multiplier was increased to x23 at single-threaded load and to x22 at higher loads.
It is when we tried to overclock our CPU that we had a problem. The mainboard would start up and pass the POST normally, but then it would restart every time it tried to boot the OS up. We thought that the CPU voltage might be set up incorrectly in the Offset mode (when it is not fixed at a certain level, like in the Manual mode, but is added to the default level, which keeps Intel’s power-saving technologies up and running).
But in fact, we didn’t even have to overclock our CPU to experience the described problem. If we but increased the CPU voltage by a mere 0.00625 volts and left the rest of the parameters at their defaults, the mainboard couldn’t boot the OS up anymore! As it turned out, the mainboard increased the voltage in the Offset mode correctly and the root of the problem was in the Load-Line Calibration option. If you turn it off, the mainboard easily boots the OS up even when the CPU voltage is increased. If this option is turned on or set at Auto, the mainboard will be restarting all the time. We only wonder why the Load-Line Calibration option is enabled when all the parameters are at their defaults except that the CPU voltage is increased by just a bit.
By the way, we guess we should also mention a couple of typical downsides you can find in the BIOSes of ASUS mainboards. First, they do not show you the default CPU voltage explicitly. They can correctly set it in the Auto mode, but you can only see it in some monitoring tool. Second, it is impossible to fix the CPU voltage at its default level. Well, we can do that formally if we enter the required value in the Manual mode, but then this voltage will always be the same irrespective of load and will not be decreased in idle mode. That is, this would effectively turn off all the power-saving technologies implemented in Intel CPUs.
We can alternatively set the CPU voltage up in the Offset mode, but it will be automatically increased by the mainboard if you select the Auto value. Therefore we have to increase the voltage in very small steps, by 0.00625 volts in our case, to keep it as close to the default one as possible. Alas, even this small increase in voltage provoked the problem we’ve described above.
Load-Line Calibration is indeed a handy and useful, but not obligatory option for overclocking. Trying to maintain the same level of voltage on the CPU when the latter is doing some heavy computations, and often exceeding the default voltage level at that, this technology is meant to prevent the CPU voltage from getting dangerously high. When the CPU is idle and enables its power-saving technologies, its voltage is lowered, yet remains high enough even for overclocking because there is no CPU load and the CPU frequency is reduced by those power-saving features. So, we only need an increased voltage when the CPU is working hard, and that’s when Load-Line Calibration comes into play, ensuring stability of the overclocked system. Thanks to that technology we managed to overclock our CPU up to 3.9 GHz on other mainboards without formally increasing its voltage: the voltage was increased by Load-Line Calibration when that was necessary, i.e. at high loads.
Thus, it is clear that we can do without Load-Line Calibration if we increase the CPU voltage manually. As we found out, our CPU could work at 3.9 GHz (with a base clock rate of 177 MHz) when we added 0.075 volts to the default voltage. We increased that parameter in the Offset mode, keeping Intel’s power-saving technologies up and running so that they reduced the voltage and frequency of the CPU when the latter was idle.
We didn’t enjoy our success for long because we had another problem right away. The mainboard could not make the memory modules stable at 1770 MHz with 8-8-8-22-1T timings (we had used these parameters before in our reviews of the Gigabyte GA-X58A-UD5 rev. 2.0 and Gigabyte GA-X58A-UD3R rev. 2.0). Therefore we had to limit ourselves to a memory frequency of 1416 MHz. The final overclocking results are shown in the next screenshot:
We wouldn’t say that the inability of our mainboard to make the memory modules stable at high frequencies was a catastrophe. We made up for the lower frequency by selecting more aggressive timings, namely 7-7-7-20-1T. Therefore we hope the difference from Gigabyte’s mainboards with their memory frequency of 1770 MHz and timings of 8-8-8-22-1T won’t be big. By the way, there is one positive thing to the ASUS mainboard’s failure. We had had to increase the voltage of the CPU-integrated memory controller with the Gigabyte mainboards to achieve stability. And the increased voltage has a negative effect on power consumption, of course. With the Sabertooth X58 we didn’t have to increase the memory controller voltage at all, leaving it at its default 1.2 volts. So, we can expect the ASUS mainboard to be comparable to the Gigabyte ones in terms of performance but better in terms of power consumption. Let’s check this out right now.