Core i5-4670S in Detail
The S series consists of quad-core LGA1150 processors with a TDP of 65 watts - both of the Core i7 and Core i5 class. The Core i5-4670S is a midrange S series model which has typical Core i5 characteristics and takes one of the topmost positions in the Core i5 line-up. To be specific, it is a quad-core Haswell-based processor with a 6MB L3 cache and without Hyper-Threading support. It has an integrated graphics core HD Graphics 4600 (GT2) with 12 execution devices, which should be familiar to users of desktop CPUs. Its dual-channel DDR3 SDRAM controller supports clock rates up to 1600 MHz whereas its PCI Express 3.0 controller offers 16 PCIe lanes.
Thus, the S series only differs from their full-featured counterparts in terms of clock rates. Intel sets lower clock rates for its energy-efficient products, which also allows to set a lower voltage. The resulting processor needs less power and generates less heat. So while the regular Core i5-4670 is clocked at 3.4 GHz, the Core i5-4670S is clocked at 3.1 GHz, which is 300 MHz lower. If we consider clock rates only, the Core i5-4670S will look like the Core i5-4440 that has the same specified clock rate. However, these two processors are not identical.
The key difference is about the Turbo Boost 2.0 technology. It raises the clock rate of regular 84W quad-core CPUs by no more than 400 MHz (and the clock rate of the Core i5-4440 can only be boosted by 200 MHz), but the energy-efficient S series uses that technology in a far more aggressive way. For example, the Core i5-4670S can be boosted by as much as 700 MHz – up to 3.8 GHz – at single-threaded loads, which makes it as fast as the Core i5-4670.
We can see it clearly with the CPU-Z utility. Working at full multithreaded load, the Core i5-4670S uses a clock rate of 3.4 GHz with Turbo Boost 2.0 enabled. Our sample of the CPU has a voltage of 1.06 volts in this case, which is about 0.1 volts lower than the voltage used by the senior 84W Core i5 models.
Running a single-threaded application, the CPU is boosted to 3.8 GHz and its voltage goes up to 1.17 volts.
The following table provides a full picture of the clock rates the Core i5-4670S uses at different loads in comparison with those of the regular Core i5-4670:
It is easy to see that the biggest difference between the full-featured and energy-efficient S-indexed processors can be observed when they use 3 or 4 of their cores. The clock rates get closer at 1- or 2-threaded loads. And the HD Graphics 4600 core integrated into the i5-4670S works in the same way as in the regular CPU models.
Its active-mode clock rate is 1.2 GHz. In idle mode the integrated graphics core is clocked at 350 MHz.
Core i5-4670T in Detail
The T series is yet another energy-efficient CPU series for the LGA1150 platform. Compared to the S series, it includes CPUs with even lower TDPs: 45 or 35 watts. That’s why this series has no Core i7 modifications. It only includes Core i5, Core i3, Pentium and Celeron products. Quad-core T-series CPUs have a TDP of 45 watts while dual-core ones, 35 watts.
The Core i5-4670T we've got for our tests is one of a few quad-core CPUs with a TDP of 45 watts. Like its cousins with twice its TDP, it features a 6MB cache, a GT2-class graphics core, a dual-channel DDR3-1600 SDRAM controller, and a PCI Express 3.0 controller for 16 PCIe lanes. Its lower power consumption is ensured by reduced clock rates and voltage. From this point of view, the Core i5-4670T can be called one of the slowest desktop quad-core Haswell-based CPUs. Its specified clock rate is only 2.3 GHz.
We shouldn’t forget about Turbo Boost 2.0, though. Very important for the S series, it is even more crucial for the T series because it can raise the clock rate of the Core i5-4670T by a whole gigahertz, notching a solid 3.3 GHz at low loads. Well, even with such aggressive turbo modes, the Core i5-4670T is obviously slower even than junior 84W Core i5 models anyway. So if you choose an energy-efficient quad-core T-indexed processor, you must be aware that its energy efficiency is achieved at the expense of performance.
We can see it in its clock rates. At full multithreaded load the Core i5-4670T is clocked at 2.9 GHz. Our sample of the CPU has a rather low (for a quad-core Haswell) voltage of 1.04 volts in this case.
The peak clock rate of the Core i5-4670T is reached at single-threaded loads: 3.3 GHz, just as expected according to its specs. The voltage is increased to 1.15 volts in this mode.
The following table sums up the clock rates the Core i5-4670T uses at different loads thanks to the Turbo Boost technology:
The numbers indicate that the Core i5-4670T is slower than the regular Core i5-4670 by 15 to 20%, depending on load. This is only true for computing tasks, though. The Core i5-4670T’s graphics core is HD Graphics 4600, has 20 execution devices and a 3D clock rate of 1.2 GHz, just like ordinary Haswell-based CPUs.
It must be noted that, in theory, if a CPU's power consumption and heat dissipation go out of the designated limits, its clock rate may be dropped below the maximum levels defined for the turbo modes. This effect can often be seen with platforms that use mobile U- and Y-series CPUs. We didn't see that with our S- and T-series LGA1150 processors, though. Even at high mixed (computing/graphics) loads the Core i5-4670T kept working at 3.3 GHz and its graphics core, at 1.2 GHz. Still, we should inform you that the temperature threshold for thermal throttling is lowered from the conventional 100°C to 92°C and 85°C for the S and T series, respectively.
Core i5-4670, Core i5-4670S and Core i5-4670T: Specs Comparison
Intel makes all of its energy-efficient processors in a very simple way. When it comes to the manufacturing process, there are no differences between semiconductor dies for standard and energy-efficient Haswell-based products. It is only at the last manufacturing step that processors with low power consumption and heat dissipation are assigned lower clock rates and programmed for a different range of operating temperatures. These two simple operations are enough to categorize them into different product series which vary considerably in specified heat dissipation.
The described approach to making energy-efficient CPUs may look primitive at first, but it works perfectly for Haswell semiconductor dies and also helps keep the manufacturing cost low. Thanks to that, Intel’s energy-efficient desktop processors come at the same prices as their standard counterparts. Intel doesn’t hamper the expansion of Haswell-based S and T series processors with its pricing policy, so there is no reason for them not to get popular.