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AMD Turbo CORE Technology

One of the key enhancements in the Thuban processor family is the introduction of Turbo CORE technology – sort of AMD’s response to Intel Turbo Boost.

I would like to remind you that Turbo Boost technology implemented in Intel Core i5 and Core i7 processors implies that their clock frequency increases when not all the CPU cores are loaded with work. As a result, Intel’s contemporary multi-core processors, which usually work at lower clock frequency than the dual-core ones, perform very well not only in multi-threaded applications, but also under those types of load that cannot be paralleled that well. AMD had nothing to offer as an alternative to Turbo Boost until today, but they have finally found a way to strike back in their new six-core processors.

However, AMD didn’t keep to Intel’s hard beaten track. Phenom II X6 processors do not have any special units that would control the frequency, monitor processor temperature and their current levels interactively. In terms of microarchitecture, new six-core AMD processors are barely any different from their predecessors. That is why AMD Turbo CORE technology has been implemented in the simplest (and most straightforward) way – through expansion of the already existing Cool’n’Quiet technology. In other words, AMD Phenom II X6 processors decide if they want to increase the clock frequency basing on only one single factor: the number of utilized processor cores.

In other words, in reality AMD Turbo CORE technology works as follows: as soon as three or more processor cores switch to power-saving mode and their frequency goes down to 800 MHz thanks to Cool’n’Quiet technology, the CPU increases the clock speed of the active cores by 400 or 500 MHz (depending on the processor model). Besides, to ensure stability at higher clock speeds, the processor Vcore is also increased by 0.15 V. It is also important that despite this “automatic overclocking, the processor power consumption and heat dissipation do not exceed the declared 125 W limit: the growing power consumption of the active cores is compensated by the fact that idling cores work at 800 MHz frequency. However, I have to stress one more time that idle cores in AMD Phenom II X6 processor never get disabled completely. Although their frequency is lowered in idle mode, they receive higher core voltage, just like the active cores, when AMD Turbo CORE kicks in. I other words, AMD Turbo CORE technology does in a way harm the processor’s energy-efficiency when it work under partial operational load.

This is what AMD Turbo CORE technology looks like for the major representatives of the Thuban processor family.

So far AMD announced only two processors from this list: Phenom II X6 1090T and 1055T with 125 W TDP. Other models will be announced a little later, within the next few months. But AMD Turbo CORE technology works exactly the same way in all processor models. We checked it out using Phenom II X6 1090T as an example. Just according to the theoretical explanations, when 4 or more cores are loaded with work, they all work at 3.2 GHz frequency.

But as soon as the number of utilized processor cores goes down to 3, the clock frequency multiplier gets automatically increased and the clock frequency rises to 3.6 GHz.

It is exactly thanks to Turbo CORE technology that the new Phenom II X6 1090T processor has every right to be called AMD’s flagship solution. Although quad-core Phenom II X4 965 launched last August works at higher nominal clock frequency of 3.4 GHz, the top six-core CPU will be faster than the quad-core one in most tasks, because Phenom II X6 1090T works at 3.6 GHz when 3 cores or less are in fact utilized. To illustrate this statement we compared the performance of Phenom II X6 1090T and Phenom II X4 965 processors in Fritz Chess Benchmark, when different number of computational threads are involved into task processing.

As we have expected, there was only one case when Phenom II X4 965 turned out faster than Phenom II X6 1090T with enabled Turbo CORE technology: when four cores are involved into the application processing. It is the change of the clock frequency that explains why the six-core processor gains less performance when it switches from using three computational threads to using four threads. The performance gain is significantly higher in all other cases.

But as we have already indicated above, higher power consumption is the price you have to pay for higher performance under partial operational load. And these are not just words. The next diagram shows how power-hungry the new Phenom II X6 1090T becomes with enabled Turbo CORE technology. We used LinX 0.6.3 utility for our test. We manually limited the number of computational threads to create and measured the processor power consumption along the 12 V power line.

If one, two or three processor cores out of six are in fact loaded with work, Turbo CORE technology increases the total processor power consumption by 20-25 W. As a result, Phenom II X6 1090T processor with enabled Turbo CORE technology consumes about the same amount of power as it would if five cores out of six were in fact working full throttle. This serious increase in power consumption is obviously caused by the Vcore increase that occurs when Turbo mode kicks in.

So, AMD Turbo CORE technology has a positive effect on performance, but cannot be considered energy-efficient. However, we should keep in mind that the developers of this technology had very limited resources, because Turbo CORE should be fully compatible with the existing Socket AM3 platforms. And this is where we can’t actually complain: this technology doesn’t require any software installation, it is transparent for the system OS and works on all mainboards quite well. The only thing you need to have is Thuban processor family support in the mainboard BIOS.

By the way, I would also like to point out one peculiarity of Turbo CORE technology working on Phenom II X6 1090T processor from the Black Edition series. Since this processor is targeted for computer enthusiasts and overclockers, it allows traditional overclocking by multiplier as well as more flexible configuring of the Turbo mode. In the BIOS Setup there appears a special option for manual adjustment of the processor clock frequency multiplier used during Turbo mode activation, right next to the option for adjustment of the regular processor multiplier. This option is available on all systems supporting Turbo CORE, but exclusively for Black Edition processors.

 
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