Core i5-661 CPU Review

Introduction

Many years ago, experts predicted that in the future computer processors would have an integrated graphics processor, instead of having this component on the motherboard chipset or on a discrete graphics card. In fact, AMD was the first CPU manufacturer to announce the development of such solution, dubbed Fusion. However, it is its competitor, Intel, the first company to launch products using this idea (codenamed “Clarkdale”). Today we are going to review one of the first CPUs with an integrated graphics processor (GPU) to arrive on the market, Core i5-661.

One of the main features introduced with socket LGA1156 processors was a PCI Express 2.0 x16 controller inside the CPU. The most obvious speculation for this move was to allow the release of CPUs with an integrated graphics controller. Whoever speculated that this would come true was right.

What came as a surprise to us was the release of Core i5 CPUs using this technology. Usually integrated graphics is reserved for entry-level computers, and our best bet was that only the new entry-level CPU from Intel, Core i3, would carry an integrated graphics controller.

Intel is announcing this week six new desktop processors, four Core i5 and two Core i3, all with integrated graphics. Since the only Core i5 CPU released to date, Core i5-750, doesn’t have an integrated graphics controller and starts with the model number “7,” it is safe to assume that all Core i5 models starting with “6” have an integrated graphics controller. The models ending with “0” have this embedded graphics chip running at 733 MHz, while models ending with “1” have this component running at 900 MHz, which is the case of the model we are going to review. This rule also applies to Core i3 models. On the slide below we show the main specs of these new CPUs.

Figure 1: New Core i3 and Core i5 CPUs.

As you can see, all Core i3 and Core i5 models being released are dual-core CPUs with Hyper-Threading technology, meaning that the operating system recognize them as if they had four cores (Hyper-Threading technology emulates an additional core per CPU core; this emulated core is slower than a real core, of course). Core i5-750 is a quad-core CPU without Hyper-Threading technology. So while all Core i5 CPUs are recognized as having four processing cores by the operating system, on Core i5-6xx only two of them are “real” (the other two are emulated). Thus another difference between Core i5 models starting with “6” is the presence of two cores with Hyper-Threading technology, while models starting with “7” come with four cores but not Hyper-Threading.

Another important difference is that these new Core i5 CPUs have half the amount of L3 memory cache compared to Core i5-750 (4 MB vs. 8 MB). All other caches remain with the same size (32 KB + 32 KB for L1 and 256 KB for L2, per core).

Core i5 CPUs feature Turbo Boost technology, which allows the CPU to increase its clock when the computer demands for more processing power (as long as its temperature stays within the normal range, i.e., up to the processor’s TDP). We reviewed Core i5-661 with this feature enabled; this CPU runs officially at 3.33 GHz but when Turbo Boost is enabled it can overclock itself up to 3.60 GHz.

Like Core i5-750, all these new CPUs have an embedded memory controller supporting DDR3 memories up to 1,333 MHz under dual-channel configuration.

New motherboards are necessary for these new CPUs, since motherboards based on the previous socket LGA1156 chipset, P55, don’t have the necessary video connectors. Three new chipsets were released for these new CPUs: H57, H55 and Q57. The differences between these chipsets and a comparison with P55 are provided in Figure 2.

Figure 2: New chipsets.

All these new CPUs are built using the new 32-nm manufacturing process (the previous Core i5 is manufactured under 45-nm technology), codenamed “Westmere.” One of the main novelties brought by this new process is the introduction of six new instructions targeted to encryption (called AES-NI or Advanced Encryption Standard New Instructions).

Now let’s see the features of the new integrated graphics controller.