Abit AA8 (Intel 925X Alderwood)
Overclocking and stability
Having exhausted the marketing benefits from the "SoftMenu" concept, Abit decided to switch to the active use of "mGuru". Therefore, the first item in the BIOS settings menu is called "mGuru Utility". This section traditionally includes all the functions of "fine" tuning of the processor clock speed, memory as well as their operating voltages. In fact, the pompous name SoftMenu was not in vain: this is how the utility for overclocking from within Windows is called now.
It is especially interesting to test the overclocking features on Abit AA8. The most important intrigue is about the question "has Intel introduce protection against overclocking?? If yes, was Abit able to invent ways to bypass the protection?"
Remember that every release of new Intel chipsets is accompanied by rumors of possible blockage of overclocking features. Therefore, overclockers' attention was fixed to every new announcement of testing this or that motherboard. Up till now, all those rumors have proved unconfirmed. But this is not the case with i915/i925 :(.
Prior to moving to overclocking, let's look into the power converter. It uses a 8-channel power scheme in which there are seven 2200 mkF and four 1200 mkF capacitors.
Note the thick silvery strips on the board's textolyte. These are the so-called "Overclocking Strips" which improve cooling of the textolyte around the power module. The strips are applied on both the front
and back of the board.
Now on to the overclocking features.
First off, Abit AA8 allows adjusting the system bus speed within 100 to 300 MHz in 1 MHz increments.
Very convenient is that you can set any FSB value without scrolling the interim values.
Secondly, Abit AA8 allows adjusting the processor voltage (Vcore) within a very wide range: within 1.3875V (nominal) to 1.7375V in 0.005V increments.
The advanced user can raise the Vmem from the nominal 1.8V up to 2.25V (in 0.05V increments).
Besides, we get a useful feature for raising the chipset voltage.
The variation range is within 1.5V (nominal) to 2.05V (in 0.05V increments).
At increased speeds, it is important that the PCI bus speed, if possible, not depart from the standard 33 MHz. This is primarily important for the correct hard disk functioning. Therefore, Abit AA8 allows setting a fixed speed at the PCI bus. This parameter is adjustable within 33 to 40 MHz.
We are now moving on to the most exciting part - the practical overclocking. Unfortunately, a system based on Abit AA8 refused to run at FSB speeds higher than 216 MHz. That is, the maximum possible clock speed for a 3.2 GHz processor turned out to be 3.45 GHz.
After numerous experiments I arrived at the conclusion that there is "overclocking-proof protection" implemented at the level of Intel chipset. First, the technological limit for the Prescott core of stepping D0 is 3.8-4.0 GHz. But in our case the processor demonstrated stable operation at 3.45 GHz at the rated voltage, and refused to start up at higher speed (at any Vcore).
Normally, there exists a certain range within which the processor runs at speeds close to its limit which is possible through voltage raise, but without 100% guarantee of stable operation.
Secondly, any changes in the memory settings (decrease in frequency, raise in the latency timings and voltage) were unable to improve the overclocking results. Finally, overclocking attempts using the Windows utility SoftMenu nor allowed to overcome that 8% limit of the rated FSB speed.
The next tested board built on the i925X board (we are not yet calling its name) has brought in some corrections. In particular, the processor did overclock to 4.0 GHz at Vcore=1.5V (i.e., FSB=250 MHz) and the memory was running absolutely stably in the DDR2-666 mode.
So, even if there is the overclocking-proof protection in i925X chipset it can be overcome, and all is in the hands of the motherboard manufacturer.
By the way, the Abit SoftMenu utility is very powerful: apart from varying the FSB speed and operating voltages, it allows adjusting the rotational speeds of the fans as well as changing the memory operating frequencies,
as well as the starting window of OC Guru program.
 This utility is closely linked to the SoftMenu utility and allows setting the overclocking parameters for several users, enabling several modes (Turbo is the most powerful, Quiet is the least noisy), as well as enabling the AutoDrive feature for dynamic overclocking. Regarding the latter feature, we have repeatedly mentioned it in our reviews of MSI motherboards, but this time this feature has become accessible for the users of Abit motherboards. With the AutoDrive enabled, the system runs in the rated mode; but once a resource-hungry application starts up (e.g. a game) the board pushes up the FSB speed thus overclocking the processor giving a performance boost. On quitting the game, the system turns back to the rated FSB speed thus reducing load upon the processor and decreasing the heat emission. With reduced heat emission, the FanEQ feature automatically reduces the rotational speed of the fans and pushes down the noise level. That is, we get a comprehensive and balanced approach to the "performance/noise level" problem.
On the very last day we received a beta version of the BIOS with which the board improved its overclocking potentials. In particular, it was able to start at 250 MHz and even reached the Windows boot-up. And the completely stable operation was registered at FSB=245MHz.
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