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Closer Look at 4th Generation Intel Core i5 Processors

The model range of desktop Haswell-based processors is hardly different from the Ivy Bridge series. Like with the Core i7 series, the new microarchitecture doesn’t bring about any change in terms of clock rates, let alone other basic specs. You can easily see that in the table below (we don’t include the special S, T, and R-indexed Core i5 models in it for the sake of readability).

The updated Core i5 series includes only four models. The fifth modification, Core i5-4440, is going to be added later on. Overall, Intel intends to limit the variation so that there were just two models in each price category. That’s why it is impossible to find direct predecessors for the Haswell-based Core i5 CPUs in the Ivy Bridge series. More importantly, the Core i5 4000 series doesn’t include any models without an integrated graphics core.

Anyway, the Core i5 remains the most attractive offer for users who want to have a quad-core CPU at a reasonable price. The Haswell-based Core i5 CPUs resemble their Core i7 cousins, featuring the same 22nm semiconductor die (177 sq. mm large), but they are slower due to lower clock rates, smaller L3 cache (6 instead of 8 MB), and lack of Hyper-Threading.

The senior model in the updated Core i5 series is overclocker-friendly, which is denoted by the K index. The Core i5-4670K supports a full range of unlocked frequency multipliers and allows to overclock its x86 cores, L3 cache and memory controller. If you don’t want to pay extra for these capabilities, the Core i5-4670 model is exactly the same, minus the overclocking features. The Core i5-4670 and Core i5-4570 models may also be interesting for their support of certain security technologies (vPro, TXT and VT-d) which are missing in the K-indexed Haswell-based CPUs (in the Core i7-4770K, too). The Core i5-4430 doesn’t support vPro and TXT, either, and its lower market positioning is also reflected in its Turbo Boost 2.0 setup. While the rest of the Core i5 CPUs can dynamically increase their clock rate by 400 MHz above the specified level, the Core i5-4430 can only do that by 200 MHz.

By the way, the term “specified clock rate” loses its meaning with the Turbo Boost 2.0 technology. The Core i5-4430 is the only model that can work at its specified clock rate whereas the other Core i5 models work 200 MHz faster than specified even at full load. There’s nothing new about that, actually. Turbo Boost 2.0 did the same with the Ivy Bridge generation.

We can easily find similarities between the specs of the Haswell and Ivy Bridge based Core i5 processors. The transition to the new CPU design hasn’t provoked any increase in clock rate or cache memory amount. That’s why the Core i5-4670K and Core i5-4670 have almost the same specs as the Core i5-3570K and Core i5-3570 whereas the Core i5-4570 and Core i5-4430 models are very much alike to the Core i5-3470 and Core i5-3330. On the other hand, the newer microarchitecture can be identified by the 7 W higher TDP, support for the AVX 2.0 instruction set, and the more advanced HD Graphics 4000 core with 20 execution devices.

So when it comes to computing performance, the Core i5 4000 series are going to be superior to their predecessors through certain improvements on the microarchitectural level. There are not so many of them, yet they have an impact.

First of all, branch prediction algorithms have been improved in the front part of the execution pipeline.  The improvement is achieved by means of larger internal buffers and data structures in nearly all of the CPU’s subunits. The out-of-order execution window has been enlarged, so instructions from a single thread can be processed more efficiently in parallel to make fuller use of the CPU’s execution devices. For the first time since 2006 the number of execution ports is increased in the Haswell. There are 8 instead of 6 such ports now, so the theoretical throughput of the Haswell's pipeline has increased by a fourth. Intel has also expanded the instruction set, adding AVX2. Included into the new subset are FMA instructions that perform two floating-point operations simultaneously. Thanks to them, the Haswell's theoretical floating-point performance is doubled. To eliminate any potential bottlenecks, the L1 and L2 cache bandwidth is doubled as well.

Intel doesn’t differentiate its desktop Haswell-based CPUs in terms of the integrated graphics core. All regular Core i7 and Core i5 models are equipped with the GT2 core. Graphics of this class used to be only implemented in Intel’s K-indexed CPUs whereas the rest were equipped with the weaker GT1. But now you can choose any LGA1150 processor for a computer without a discrete graphics card and you’ll have the same graphics performance. This also refers to the Core i3 series which is to be announced in September.

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