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Adjustment ranges of CPU multiplier and voltage, as well as HT bus, depend on a given processor. We publish results for our Phenom 9550.

We used BIOS P03 dated 26.08.08, provided by the manufacturer. The mentioned BIOS parameters are available in this version, but the viability of non-standard settings hasn't been tested.

We are happy to announce that Foxconn engineers did a great job correcting the mistakes. We used to criticize almost all motherboards from this company, even models for overclockers, for unbalanced settings (they often lacked vital options, for example, HT bus multiplier control, and offered sophisticated and rarely used settings, for example, lots of minor timings). Now everything is fine, only the frequency range of the integrated graphics core can be adjusted in a narrower range than in most competing products. However, overclocking above 1000 MHz is usually accompanied by significantly raised Northbridge voltage, which is hardly justified in practice.

Overclocking

In order to evaluate motherboard and its BIOS, we overclock our testbed processor to a maximum stable level. We use all features of the motherboard in this test, including raising CPU voltage and adjusting multipliers and frequencies of system and peripheral buses, if necessary. But if, for example, reducing Hyper-Transport frequency does not improve overclocking, we leave the default multiplier. Memory is set to the standard frequency for a given memory module (multiplier correction), if a manufacturer does not publish any ways to improve memory overclocking. Otherwise, we analyze their efficiency as well. In order to evaluate stability of the overclocked system, we load Windows XP and run WinRAR performance test for 10 minutes (Tools -- Benchmark and hardware test). As overclocking potential is an individual property of a given motherboard sample to some degree, we don't set the task to determine overclocking potential to within a single MHz. In practice, we are to find out whether CPU overclocking will be limited by a motherboard as well as to evaluate its behavior in non-standard modes, including automatic restoration of a correct frequency after a failed overclocking attempt, etc.

When we overclocked the motherboard in the traditional way (by raising the clock rate aka "FSB clock"), it demonstrated almost maximum results, proving the fact that an integrated graphic core won't be a bottleneck in a well designed chipset and motherboard. Frequency of the graphics core can be raised with a corresponding option in BIOS (we used it to increase its clock rate from 700 MHz to 950 MHz, voltage increased by 0.18 V). Independence is preserved in this case as well. In other words, when we overclocked both the CPU and the integrated graphics core, the system was just as stable as in case of separate overclocking.

But strictly speaking, with the appearance of Black Edition processors (with an unlocked multiplier), such old-fashioned underground methods of overclocking the bus resemble crossing a river on a raft instead of using a bridge. It's fun tweaking BIOS options, of course. But if you just want to obtain maximum performance and maximum stability (with allowance for overclocking), it's much easily to operate only two parameters -- CPU multiplier and voltage.

However, up to recently buying Black Edition processors has been a matter of taste. What concerns Phenoms, owing to high default multipliers they usually require an insignificant raise of FSB clock even for serious overclocking (with increased voltage). Most motherboards can do that, at least among models for overclockers. Besides, any processor can be overclocked by raising the reference clock, while only several models come as Black Editions.

However, with the appearance of "mysterious" Advanced Clock Calibration in SB750 Southbridge, processors with the unlocked multiplier become a technically expedient choice (taking into account democratic prices for Phenom X4 9850 Black Edition, such processors are economically expedient as well). We've set ACC +2% (for all cores) and obtained extra 400 MHz to the result without ACC. We were surprised to see the overclocking potential so expanded and full stability at such frequencies. With disabled ACC, further overclocking resulted in startup failures, and raising the voltage by any value was of no help (these facts suggested that the overclocking potential was squeezed dry). Note that ACC is effective only when you overclock the system by increasing the multiplier. At least we've seen it in two Phenom processors (see the table above). This technology had absolutely no effect on Phenom X4 9550, overclocked by raising the bus frequency. The same with the 9850. When we tried to overclock them above 2900 MHz by raising the bus frequency, the system immediately responded with instability. By the way, when we installed an Athlon processor, the ACC option disappeared in BIOS menu. So we couldn't check whether this technology can squeeze extra MHz from unlocked models of this series. From the look of it, the official recommendation from AMD to enable ACC only for Phenom Black Edition processors is well grounded.

But let's get back to overclocking tests of our motherboard from Foxconn. We should add that it requires manual reset, when the system freezes (which is facilitated by the on-board buttons). But it automatically cleared all BIOS settings, including even the order of bootup devices (that's a problem for modern users, spoiled by smart methods of restoring critical startup parameters).

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