AMD Phenom II X6 1075T/X4 970/X2 560 and Athlon II X4 645
Overclocking – Air
We have started overclocking a little bit differently this time. Initially, we just went for highest stable clock. We still do that, but for those who want to take the lower-risk road (which has lower returns), we also find the maximum stable overclock with the processor’s stock voltage. We run it through IntelBurnTest on maximum stress (4GB of RAM installed) for 5 passes. We could do more, yes, but we are limited by time here. After finding the maximum stable stock voltage OC, we find our benching speed, which we get through overvolting. We use the highest stable speed that can produce reliable and consistent results without crashing. No fancy stress testing here, as the heat may cause instability in an otherwise stable processor.
First up, the Athlon II X4 645. We were able to achieve 3.5GHz stable on stock volts, and, even with voltage going as high as1.525v, couldn’t budge above 3.7GHz. Our previous Athlon II X4 we reviewed wasn’t a terribly great overclocker, either.
Next up, the Phenom chips. The Phenom II X2 560 was able to beat out the Athlon II X4 on its maximum stock voltage overclock at 3.72GHz, which is respectable. We hit a maximum overclock of 4.2GHz, and settled at 4.1GHz for benching. We were unable to unlock the extra 2 cores. Too bad, but luck is the name of the game when it comes to core unlocking; sometimes it just doesn’t work and we were unfortunately on the wrong side this time.
Our Phenom II X4 970 was able to hit a remarkable 4GHz without so much as a voltage increase. Very impressive when you think that older AMD chips needed some very chilly temperatures and strong voltage to even think about such speeds. Naturally, though, your results may vary, not all chips overclock the same. In this case, though, the model that we used to hit 4GHz will be the same revision that will be hitting stores, so it is entirely likely that it will be doable with retail models. Upping the voltage, we were able to achieve a bench speed of 4.2GHz. It booted at 4.4GHz, for fun, but was unstable.
The most interesting of the lot was the Phenom II X6 1075T. We were initially astonished by how little voltage it had displayed in HWMonitor/CPU-Z, at 1.25V for a 3GHz hex-core. At that voltage, it ran up to 3.5GHz, the speed of the turbo; thus, it was running at the turbo speed without having to clock down additional cores. However, we soon realized that the stock voltage for the chip was 1.425V, our motherboard shortchanged us .2V. The fact that the chip ran like a champ and could even overclock while severely undervolted was fantastic to say the least. At the regular stock voltage, it hit 4GHz. Awesome overclockability on these chips. We added .02V to the stock voltage and got our benching speed of 4.2GHz.
Each of our Phenom II chips hit 4GHz and beyond – awesome.
Let’s move onto subzero overclocking next.