I personally am a big fan not only of overclocking, but also of different power-saving technologies. I like it when the CPU works at the maximum of its potential only when it is really necessary, but is energy-efficient and quiet in idle mode. However, I am sure that there are people among our readers who mostly care about hitting the maximum processor frequency and do not really bother about high power consumption in this case. That is why we decided not to resort to any power-saving technologies and set the processor core voltage using “Static CPU Voltage Override” parameter and not “Dynamic CPU Voltage Offset (mV)” as we have just done before. Unfortunately, even this approach didn’t help us avoid CPU Vcore drop under heavy load or its extreme increase when e enabled VDroop function.
The next two graphs will show in a more illustrative way what happens when we change the “Enhanced Power Slope” value. The first graph shows a system overclocked to 185 MHz base frequency with dynamic implementation of Intel Turbo Boost technology. To ensure processor stability during this overclocking attempt, we used “Dynamic CPU Voltage Offset (mV)” parameter to add another 0.055 V (55 mV). We are not going to protect ourselves against processor Vcore drop. “Enhanced Power Slope” parameter set by default to “100% Slope”. The preliminary system stability test was performed using ten runs of LinX test.
First of all, we are interested in checking out the dynamics of processor voltage changes: its graph is green and is built along the left axis. Before the bests started, the CPU was idling, Intel processor power-saving technologies were up and running and the CPU received only 1.11 V. Right after we launch LinX test utility the voltage increases, but then drops immediately to 1.15 V under heavy load. Later on we see the same things repeat all over again: in the intervals between calculations the voltage increases to 1.27-1.29 V, but under heavy load it rapidly drops to 1.15 V. The processor temperature graph is in red color and built along the right axis. In idle mode the core temperature is about 40 °C, during the tests it increases almost to 80 °C and then goes down again when the test is complete.
The amplitude of voltage fluctuations is relatively big, because we are not protected against processor voltage drop under heavy load. But luckily, even a low voltage of 1.15 V is enough to ensure stability of our Intel Core i7-920 processor overclocked to 3.7 GHz. When we use dynamic Intel Turbo Boost implementation, the processor clock multiplier remains equal to 20x under heavy load created by eight computational threads of LinX utility. With 185 MHz base frequency it produces 3.7 GHz resulting CPU speed. If we decide to switch to static Intel Turbo Boost, then with 21x multiplier the CPU frequency will increase to 3.9 GHz and 1.15 V Vcore will no longer be enough. This is when we need to protect ourselves against voltage drop that is why we set “Enhanced Power Slope” parameter to “No Slope” and run our LinX test one more time without making any other changes.
The startup voltage remained the same: 1.11 V, however the system started acting differently during the test. Fluctuations amplitude got much smaller; the protection against voltage drop is obviously working fine. The minimal processor core voltage is 1.22 V in the beginning of the very first computational cycle, but even before the end of it the core voltage increases to 1.23 V and then to 1.24 V, and later on almost never drops below 1.25 V. the maximum Vcore between the test cycles is at first 1.3 V and then gets even higher than that. The temperature increases gradually reaching the maximum of 97 °C. This time we failed the test even without switching to the static Intel Turbo Boost implementation when the multiplier increases to 21. We saw the blue screen of death during the sixth test cycle.
If you have been reading our review attentively enough, you will remember that processor Vcore has been increased right from the start to ensure stability during overclocking when no protection against voltage drops is in place. However, now when we enable VDroop function, there is no need to increase the voltage anymore and additional volts will only heat up the CPU excessively. Everything is absolutely correct: we haven’t changed a thing except for the “Enhanced Power Slope” parameter for the sake of comparison. In fact, even if we leave the processor core voltage at its nominal of 1.225 V, it will still increase eventually beyond 1.3 V when we enable protection against voltage dropping. And that is way too high. It causes the temperature to hit 98 °C and prevents us from using VDroop function. That is why we couldn’t get our overclocked processor to work stably with a constant multiplier under heavy loads.
Unfortunately, Intel DX58SO proved to be no universal mainboard. It is a real pity. However, it doesn’t diminish any of its advantages and strengths. As you remember, dynamic implementation of Intel Turbo Boost technology did allow us to achieve very good results during overclocking.