All overclocking experiments were performed in an open testbed configured as follows:
- Gigabyte GA-EP45-DS3 mainboard, rev. 1.0, BIOS F6;
- Intel Core 2 Duo E8400 (3.0GHz, FSB 333MHz, 6MB, Wolfdale, rev. C0);
- Intel Core 2 Quad Q9300 (2.5GHz, FSB 333MHz, 6MB, Yorkfield, rev. M1);
- 2x1024MB Corsair Dominator TWIN2X2048-9136C5D;
- NVIDIA GeForce 8800 GTS 320MB graphics card;
- Seagate Barracuda 7200.10 HDD (ST3320620AS), 7200RPM, 16MB, SATA 320GB;
- Zalman CNPS9700 LED CPU cooler;
- Antec NeoPower HE 550 PSU (550W).
At first we lowered the Intel Core 2 Duo E8400 processor clock frequency multiplier to the minimal x6 in order to determine at what maximum FSB frequency Gigabyte GA-EP45-DS3 can remain stable. We decided to start with 480MHz and the board did well at this frequency. However, we couldn’t move any further than that for a while. The board would most often boot, but failed to load Windows and if it did, it would immediately terminate any stability tests we ran.
I have to say that the log of my numerous attempts suggested several theories explaining this strange behavior of Gigabyte GA-EP45-DS3 mainboard. AT first I thought that I had to disable all processor power-saving technologies to improve the result, however, practical experiments proved this supposition wrong. Then I discovered that the memory voltage could not be raised beyond 2.1V, however, test results eliminated this supposition, too. The real reasons turned out much simpler and sadder. Gigabyte GA-EP45-DS3 mainboard simply couldn’t work stably at FSB frequencies approaching 500MHz and nothing can actually change that.
Sad, but not fatal. New processors keep coming out pretty regularly, their frequencies and clock multipliers increase, so successful overclocking doesn’t necessarily require the system to work at high FSB frequencies. For example, our Intel Core 2 Duo E8400 can overclock to 4.1GHz, so if you leave its default clock multiplier at x9, then all you need is 455MHz FSB to achieve this maximum CPU frequency. Let’s check it out? Unfortunately, this attempt failed. No problem, we actually know quite a few cases when mainboards couldn’t get the CPU to work stably at 455MHz, while at 450MHz everything worked fine. It is not that big of a difference. However, we failed again. Only at 445MHz FSB the mainboard could go through with the tests. In other words, Gigabyte GA-EP45-DS3 mainboard not only failed to hit high FSB speeds, but also failed to overclock the test CPU to its maximum.
The interesting thing is that when we switched to quad-core Intel Core 2 Quad Q9300 processor overclocking, Gigabyte GA-EP45-DS3 did well and reached 465MHz FSB frequency. Of course, it is not 475MHz that we managed to squeeze out of abit IP35 Pro, and definitely not the 490MHz demonstrated by ZOTAC nForce 790i-Supreme. However, it is indeed very close to the average FSB frequencies that other mainboards reach during quad-core processor overclocking.