Overclocking Experiments

We ran our tests in an open testbed configured as follows:

• Mainboard: Gigabyte GA-EP45-DQ6, rev. 1.0, BIOS F11;
• CPUs:
  • Intel Core 2 Duo E8400 (3.0GHz, 333MHz FSB, 6MB, Wolfdale, rev. C0);
  • Intel Core 2 Quad Q9300 (2.5GHz, 333MHz FSB, 6MB, Yorkfield, rev. M1);
• Memory: 2x1024MB Corsair Dominator TWIN2X2048-9136C5D;
• Graphics card: NVIDIA GeForce 8800 GTS 320 МБ;
• HDD:  Seagate Barracuda 7200.10 ST3320620AS (7200RPM, 16MB, SATA 320GB);
• CPU cooler: Zalman CNPS9700 LED;
• Thermal compound: Noctua;
• Antec NeoPower HE 550 PSU (550W).

It occurred to me only now that since Gigabyte mainboards on Intel P45 Express chipset have BIOS Setup with very similar functionality, the overclocking potential of Gigabyte GA-EP45-DQ6 may be also similar to that of Gigabyte GA-EP45-DS3, which is not very good. At first we checked the board’s stability with Intel Core 2 Duo E8400 processor in its nominal mode. We noticed no problems whatsoever. The board did in fact set the memory frequency at 1066MHz and the timings corresponded to the BIOS settings, too: 5-5-5-14-2T. Performance Level in this case was equal to 6 and the board increased the memory voltage 2.1V by itself. I assume it has reads it off the extended EPP profile. Excellent result for the nominal mode.

Then we prepared for CPU overclocking experiments that should reveal the overclocking potential of this board. We lowered the processor clock frequency multiplier to the minimal possible value of x6. We changed the default Turbo setting of the Performance Level parameter for the memory to Standard and set 1:1 divider to the FSB speed. Without changing anything else with all the other settings at the nominal values we set the FSB frequency to 500MHz and tried to boot. The attempt was a success, the board loaded the operating system. At 520MHz, however, we had to stop: the board would only boot at best.

Well, time has come for us to check out the settings the mainboard uses for automatic overclocking. Unfortunately, monitoring capabilities of Gigabyte GA-EP45-DQ6 mainboard do not allow us to see all the parameters we are interested in. PC Health Status section only shows us the processor core and memory voltages, that is why we turned to Gigabyte’s brand name EasyTune 6 utility for help. I was about to say “had to turn for help”, but frankly speaking this utility in its current condition is a rare and maybe even the only manufacturer’s utility out there that is easy and convenient to use. We have already discussed it in detail in our Gigabyte GA-EP45-DS3 review.

It turned out that the board sets very high CPU Termination and CPU PLL voltages, while the chipset North Bridge voltage increased only to 1.4V, which is not enough in this case. We increase MCH Core to 1.46V and the mainboard starts moving up the overclocking pedestal with triumph. Gigabyte GA-EP45-DQ6 easily copes with 520, 525, 530 and 540MHz FSB frequencies without any effort. It stalls for a second at 550MHz, but we increase the North Bridge voltage to 1.48V and even this frequency gets passed with flying colors.

Gigabyte GA-EP45-DQ6 evidently copes very well with high FSB frequencies. However, the CPU in this case was working with the minimal x6 multiplier and its resulting frequency barely exceeded 3.0GHz. Will we be able to overclock it to its maximum of 4.1GHz for this particular sample with the same high FSB frequencies? Our calculations suggested that we could achieve 4.1GHz by setting the FSB at 547MHz and using x7.5 clock frequency multiplier. So, we adjusted all the necessary settings in the BIOS, the system loaded Windows and right after we started Intel Burn test we got the notorious blue screen of death.

The reasons for that were immediately clear: hurrying to succeed, we set the right multiplier, increased the voltages but forgot to lower the FSB to 547MHz, which is way beyond the capabilities of our test CPU.

However, even with the correct parameters we couldn’t achieve stability at 4.1GHz frequency. And again, we were in too much hurry, we didn’t even check if the board can ensure processor stability at such higher frequencies altogether. So, we increase the multiplier to the maximum of x9, set the FSB frequency at 455MHz. In this case, the memory or bus frequencies cannot possibly be too high to hinder overclocking, however, we still cannot pass stability tests. Then we reduce the FSB frequency just by 5MHz, i.e. from 455MHz to 450MHz. Very little, indeed, but it turns out more than enough for successful pass in all stability tests. The resulting CPU frequency in this case is 4.05GHz (450x9).

Now that we know how far the board can overclock this processor let’s calculate what bus frequency we have to set for a CPU with x7.5 multiplier so that we could hit 4.05GHz frequency. It appears to be 540MHz (540x7.5=4050). So, once the correct parameters are set, the board passes all tests just fine!

We have to say that this Intel Core 2 Duo E8400 processor sample has been used in our lab since the beginning of this year. We have tested over a dozen of mainboards of various types from different manufacturers since then. But we had to lower the processor frequency multiplier to x7.5 only once, when we tested MSI X48 Platinum mainboard. And now it is the second time, due to excellent overclocking potential of Gigabyte GA-EP45-DQ6. However, besides this indisputable advantage, MSI mainboard turned out to have a number of frustrating issues, unlike our today’s main hero - Gigabyte GA-EP45-DQ6.

Even at this early stage we can say that Gigabyte GA-EP45-DQ6 deserves the highest score for its remarkable success during Intel Core 2 Duo E8400 overclocking. However, overclocking this CPU is not enough. To achieve high resulting performance, the memory should also work stably and efficiently. As you remember, we had some concerns about it since the mainboard would set 5-7-7-25 timings instead of 5-5-5-14 timings in automatic mode.

Luckily, these concerns didn’t prove right. Further testing revealed that the mainboard reacts adequately to changes of the memory subsystem operational modes. At first we changed Performance Enhance parameter from Standard to Turbo. The board did well, although the timings changed from 5-7-7-25 only to 5-7-7-24. Then we manually set the timings to 5-5-5-15. It corresponds better to the abilities of our Corsair Dominator TWIN2X2048-9136C5D memory modules working at 1080MHz frequency. And again the system remained stable at 450MHz FSB with the CPU overclocked to 4.05GHz. The board increased its Performance Level setting to 11 in this case. We decided to see what happens if we lower it to 10, and the board once again proved confidently stable!

Well, at this point we have every right to state that Gigabyte GA-EP45-DQ6 overclocks processors and memory outstandingly. However, so far we have only used a dual-core processor, while as we know, it is quad-core CPUs that cause most problems during overclocking. So, let’s proceed.

Most mainboards usually stall at around 450MHz FSB during quad-core processors overclocking. Many boards cannot hit even this frequency, even though they can do much better with dual-core CPUs. The record during Intel Core 2 Quad Q9300 has long been held by abit IP35 Pro mainboard that managed to overclock our test CPU to 475MHz FSB. No other mainboard we have tested so far could get even close to that frequency. We even believed that this is the maximum for our CPU sample. However, this summer ZOTAC nForce 790i-Supreme came into the picture and managed to raise the stability bar to 490MHz FSB and after a little effort on our part to the phenomenal 495MHz FSB. Let’s see how well Gigabyte GA-EP45-DQ6 will do here.

The tests showed that the board can load the operating system with the CPU overclocked to 450MHz FSB, 470MHz FSB and even 490MHz FSB. However, at 500MHz FSB we couldn’t achieve stability for a while, and once we did, we couldn’t repeat the same success again. We failed at 495MHz FSB as well, however at 490MHz the repeated test was passed fine.

So, what can we say? We have seen quite a few mainboards that can overclock dual-core processors and memory pretty well. We know a few solutions that can overclock quad-core CPUs better than the others. But we haven’t yet come across a mainboard that would have such a great balance of features like Gigabyte GA-EP45-DQ6.