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Overclocking Results

Does 790FX + SB750 = High-End Overclocking?
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Most readers have seen AMD’s overclocking utility, and many have heard about huge overclocking gains made possible by using Advanced Clock Calibration (ACC) on SB750-equipped motherboards. Unfortunately, we didn’t have similar results this time.

Our first problem with AMD Overdrive is that it didn’t initially support ACC when ACPI was enabled. Meanwhile, upgrading to version 2.1.4 solved that problem.

Overdrive includes advanced features such as automatic overclocking with stability tests, but our system would lock each time it reached approximately 2.94 GHz on either motherboard. Our second problem was that the settings were lost upon restart, so the program never really finished.

Our third problem was that while ACC adjustment did appear to have some effect on overclocking capability, it wasn’t enough to get us over 3.00 GHz when using AMD Overdrive to make remaining adjustments. Our best overclocking results were achieved the old fashioned way, through BIOS voltage and clock speed controls.

With a mere 20 MHz lead over MSI’s nForce 780a SLI motherboard, the win by Foxconn’s A79A-S certainly didn’t lend any credence to the advanced capabilities of SB750-equipped motherboards. Furthermore, the SB750-equipped M3A79-T Deluxe didn’t even match the nForce 780a SLI.

Anyone worried about how the A79A-S has only “half as many” voltage regulator phases as the M3A79-T Deluxe can rest easy with the above overclocking results, as there are plenty of other more pressing limitations. We don’t know if the M3A79-T Deluxe’s voltage regulator is overkill or if the A79A-S components are simply upsized, but we can see that the board with the fewest regulator components had the best overclocking stability.

Putting aside ultimate CPU stability, we also realize that some buyers don’t have an unlocked “Black Edition” Phenom and must instead overclock using the HT base clock. It’s often possible for such systems to run out of HT overclocking capability long before the processor reaches its limit, so we tested each motherboard to find out how far its HT clock could be pushed starting at the 1,200 MHz data rate and increasing the base clock incrementally.

Phenom users who would otherwise be significantly limited by a relatively low-core multiplier will find excellent results with the Asus M3A79-T Deluxe.

One of the more exciting performance features of Phenom processors is support for DDR2-1066 memory, yet using the highest memory ratio can again limit how far the HT base clock can be pushed. Due to the popularity of 4 GB configurations, we used 2 GB modules for this test.

Foxconn’s A79A-S has slightly better memory overclocking stability with two modules installed, while the Asus M3A79-T Deluxe isn’t bogged down as much by four. MSI’s 780a SLI motherboard isn’t far behind either 790FX + SB750 sample.

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