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Pentium G850/G840/G620 vs. Core i3-2100T

Pentium processors for LGA1155 systems turned out the most energy-efficient processors with 65 W TDP. This thermal envelope has obviously been declared with a significant reserve: even under maximum load they consume considerably less power. However, Intel doesn’t want to set a lower official TDP for marketing reasons. Processors with 45 W and 35 W TDP are part of a separate business for Intel. Products like that are in demand and therefore sell at higher prices.

But we don’t really care much about the official specifications. Therefore, we decided to compare the new Pentium CPUs against one of the energy-efficient LGA1155 Core i3 processors. This comparison poses special interest to us, because CPUs with lower TDP work at lower clock speeds, which means that 65 W Pentium G850, G840 and G620 may suddenly become direct competitors to the 35 W Core i3-2100T. Energy-efficient Core i3-2100T supports Hyper-Threading technology, but its clock frequency is only 2.5 GHz. As for Pentium G850/G840/G620, their Hyper-Threading support is disabled, but their clock frequencies are 100-400 MHz higher.

If the new Pentium processors show similar heat dissipation levels as Core i3-2100T and perform at least as fast as the latter, we will get a great opportunity to save a few tens of dollars on a CPU when building an energy-efficient system.

In fact, we decided to dedicate a separate short test session to investigation of this assumption. Within this test session we tested Mini-ITX platforms built on LGA1155 Pentium processors and Core i3-2100T, which use integrated graphics. Besides, we also tested an LGA1156 platform with Pentium G6960 (Clarkdale generation).

During this test session we used the following hardware and software components for our testbeds:

  • Processors:
    • Intel Core i3-2100 (Sandy Bridge, 2 cores, 3.1 GHz, 3 MB L3);
    • Intel Pentium G850 (Sandy Bridge, 2 cores, 2.9 GHz, 3 MB L3);
    • Intel Pentium G840 (Sandy Bridge, 2 cores, 2.8 GHz, 3 MB L3);
    • Intel Pentium G620 (Sandy Bridge, 2 cores, 2.6 GHz, 3 MB L3);
    • Intel Pentium G6960 (Clarkdale, 2 cores, 2.93 GHz, 3 MB L3);
  • Mainboards:
    • ASUS P8H61-I (LGA1155, Intel H61 Express);
    • Gigabyte GA-H55N-USB3 (LGA1156, Intel H55 Express).
  • Memory — 2 x 2 GB DDR3 SDRAM (Kingston KHX1600C8D3K2/4GX):
    • DDR3-1067 7-7-7-21 with Pentium G6960 and Pentium G620 processors;
    • DDR3-1333 9-9-9-27 with Core i3-2100T, Pentium G850 and Pentium G840 processors;
  • Hard drive: Kingston SNVP325-S2/128GB.
  • Power supply unit: Tagan TG880-U33II (880 W).
  • Operating system: Microsoft Windows 7 SP1 Ultimate x64.
  • Drivers:
    • Intel Chipset Driver;
    • Intel HD Graphics Driver;
    • Intel Management Engine Driver;
    • Intel Rapid Storage Technology

Let’s start with the most interesting results: the actual power consumption. As always, the numbers below show the power consumption after the PSU and our testing methodology doesn’t take into account any power losses that occur in it.

In idle mode the system with energy-efficient Core i3-2100T inside is about 2-3 watt more economical than a similar platform with Pentium processors. So, we have no formal complaints about CPUs with 35 W TDP. The T-series processor does in fact consume less than the least energy-hungry representative of the 65 W series. However, the practical advantage of only 3 watts is, in fact, negligible. Therefore, we can conclude that Pentium processors look very good in a compact LGA1155 platform, especially against the background of Pentium G6960.

During full utilization of the processors’ computational cores things barely change. Core i3-2100T has a tiny advantage of 3-5 W over the new Pentium CPUs. So, looks like we could really argue about Intel’s positioning of the new Pentium G850, G840 and G620. These processors have every right to be considered energy-efficient, too. And the total power consumption reading for an LGA1155 system with a new Pentium inside is clear indication of that: 35-40 W is very little for an entire platform.

Nothing changes when the heaviest load falls onto Intel HD Graphics core. Systems with Pentium G850, G840 and G620 prove much more energy-efficient than the integrated LGA1156 platforms. Their power consumption readings get very close to that of a platform with a 35 W Core i3-2100T.

Although Quick Sync technology is disabled in Pentium CPUs, the hardware HD video decoder is still there. Therefore, Pentium G850, G840 and G620 based systems consume very little power during video playback.

Overall, LGA1155 Pentium processors look very appealing in terms of power consumption. They will undoubtedly fit perfectly into HTPC or compact and quiet systems concept. The absolute power consumption readings indicate that systems built with them could do just fine with low-capacity PSUs and small cooling systems. The special 35 W processors like Core i3-2100T won’t offer any serious advantage in power consumption aspect over the new Pentiums, even though they are much more expensive.

Maybe the high price of the Core i3-2100T will be justified by their higher performance? Let’s check it out now.

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