Core i3-2105 vs. Phenom II 970 X4 – the Importance of Hyper-Threading in Gaming

Today we are going to examine Intel’s Core i3 dual-core architecture and we will focus on the importance of Hyper-Threading (HT) in PC gaming.  We will compare the Core i3-2105’s performance against a similarly-priced AMD Phenom II Quad-Core CPU by using a GTX 580 for both platforms.  We will also look at the performance of Core i3-2105’s integrated HD 3000 Graphics – Intel’s premium Integrated Graphics (IG) – to see if it is sufficient for light DX10 gaming at 720P.

Our last CPU evaluation introduced AMD’s new FX ‘Bulldozer’ architecture as we focused on performance in 20 modern games.  We compared AMD’s new 8-core flagship, the FX-8150, versus Intel’s overclocked Core i7-920 and the overclocked Phenom II 980 BE X4.  We concluded that the FX-8150 required a lot of power and overclocking to beat the Phenom II and to approach the Core i7’s performance in gaming.  This time, we are taking a look at Intel’s enthusiast entry-level enthusiast CPU, the dual-core, Core i3-2105, and comparing it in gaming against the similarly-priced quad-core, Phenom II 970 X4.

We notice that AMD’s new A-series APU is positioned against Intel’s enthusiast CPU line-up and A8-3850 is set directly against the Core i3-2105. However, the Phenom II is also current and we need to look at pricing to see that the 3.1GHz Core i3-2105 is 134.99 at Newegg, while the 3.5GHz Phenom II 970 X4 – 3.5GHz – is $139.99 at Newegg.  We could have also picked the $129 3.4GHz Phenom II Phenom II 965 X4 as 100MHz makes very little performance difference.  Please note that these Phenom II quad-core CPUs regularly overclock to about 3.8GHz to 4GHz while the Intel Core i3-2105’s core cannot be overclocked; only the base clock can be raised to perhaps around +3-5% (which overclocks everything including the PCIe and memory buses).

Core i3-2105’s built-in HD 3000 Graphics

One important new feature of Intel’s new Core i3 CPU – like its big i5/i7 brothers on the LGA 1155 platform – is that Intel’s latest DX10.1 HD 3000 graphics is integrated directly into the CPU.  Since lower priced systems are the ones depending on integrated graphics, it makes sense to make this feature available to Core i3.  AMD’s new APUs also provide Integrated Graphics (IG), but the older Phenom II processors do not.  That means that you must buy a discreet video card or spend more for a motherboard with IG just to run your PC at all.

The Core i3-2105 is a dual-core processor with HT enabled and with a 3MB L3 cache very much like the Core i3-2100. There is no turbo boost found on any Core i3 CPU, but you still get Quick Sync. The only differences between these two parts is that the Core i3-2105 is priced a little higher and has an Intel HD Graphics 3000 core vs HD 2000 Graphics 2000 in the i3-2100.  This is a big deal as the Intel HD Graphics 2000 only has six execution units while the Intel HD Graphics 3000 has twelve execution units that operate at the same clock speeds.  If you need GPU performance and play games, the Intel Core i3-2105 is a better buy as the price difference is less than most entry-level discrete video cards that you would need to supplement the non-IG Core i3-2100 or the Phenom II.

Buying a discrete video card is never an issue for PC gamers as IG (integrated graphics) performance is never sufficient for them.  However, we will benchmark our Core i3-2105’s integrated graphics at 720P so that you will know what to expect in light gaming.  IG is also very useful for watching HD video and/or to troubleshoot your discrete video

Phenom II architecture is Old

Phenom II architecture is old and relatively unchanged for about the past 6 years, and it has recently been supplanted by AMD’s new FX architecture (Bulldozer).  We are looking to see how Phenom II holds up against Intel’s newest Sandy Bridge Core i3 architecture in gaming and if the Phenom II’s higher clockspeed and two ‘extra’ cores can compensate for Core i3’s architectural refinements, Hyper-Threading (HT), and better IPC (instructions per clock).  We are also going use our 20-game benchmark suite at 1080p with a GTX 580 to see how Core i3’s dual-core 3.1GHz with Hyper-Threading (HT) compares to AMD’s quad-core Phenom II at +400MHz higher stock clock.  Then we will disable HyperThreading to compare performance of the Core i3 with HT on versus HT off.

The Core i3 Architecture

AMD has been working on its new FX CPU architecture since long before Phenom II. Phenom II reached its performance peak in gaming with the 980 Black Edition (BE) which we reviewed here a few months ago. It is AMD’s fastest 4-core processor and it sports a stock CPU speed of 3.7GHz. We underclocked our 980 BE using its unlocked multiplier down to 3.5GHz as that is the stock speed of the Phenom II 970 X4 which is priced about the same as the Core i3-2105.

We are using the GTX 580 on both platforms to give you a comparison of our two CPUs scaling in games at the most popular 1080p resolution and at the maximum details that gamers play at.  This video card is the most powerful single-GPU stock card available and it will minimize the effects of both “GPU bottlenecking”, and its use will lessen potential issues with demonstrating the effects of Hyper-Threading on gaming performance by our Core i3-2105.

The Core i3-2105 has a pair of identical 3.1GHz Sandy Bridge cores, and is rated at a TDP of 65W. As with the other Core i3 CPUs, they have a 3MB pool of shared L3 cache, along with a pair of 256KB L2 cache pools (one for each core) and a pair of dedicated 64KB pools of L1 cache (again, one per core).

Probably the main advantage offered by the Core i3-2105 is Hyper-Threading. HT generates two logical cores from their pair of physical cores, with all four cores appearing in the operating system. HT gives the processor a boost in multi-threaded tasks, although it is not as efficient than having four physical cores like the Phenom II Quads (and the A-series APUs), as we shall see.

The Chipsets – Z68 versus AM3+

The Z68 chipset is the premium chipset for Core i3 which supports both CPU multiplier and IGP overclocking (for unlocked Intel CPUs), Quick Sync, and SATA 6.0Gbps as well as PCIe 3.0 when Ivy Bridge is released. It also supports Intel Virtu Technology, which uses the IG for less demanding tasks and the discrete GPU for more intensive applications, saving energy.  With this chipset, Intel introduced their Smart Response (SSD caching) which is exclusive to it.

The Chipset is LGA 1155 and this is its simplified block diagram.

Below is ASRock’s Z68 motherboard.

We are using the ASRock Z68 Extreme3 Generation3 LGA 1155 motherboard which we purchased from Newegg for $125.  It is very full-featured and easy to use and setup.  It is excellent bang-for-buck and highly recommended!  Like most LGA 1155 motherboards, it supports 8x+8x PCIe for SLI and CrossFire.  We hope to have a review of it at ABT as well as of our ASUS AM3+ CrossHair V motherboard soon.

For the Phenom II X4 Quad, we are using ASUS’ flagship AM3+ Crosshair V motherboard which costs over $100 more than the ASRock board.  We got ours as a review kit from AMD/ASUS for evaluating the FX-8150 last month.  It is a awesome and fully-featured AM3+ board that is a joy to use – especially for its superb overclocking functions.  It also supports 16x+16x PCIe bandwidth and PCIe 3.0 as well as SATA 3.0 specifications.

Specifications

Here are the i3-2105 specifications from Intel’s web site:

AMD’s Phenom II X4 Quad core versus Intel’s Sandy Bridge dual Core i3

AMD is positioning their top Phenom II quad-core CPUs against Intel’s lower midrange – specifically against the Core i3.  The Phenom II looks great on paper with 4 cores against Intel’s Hyper-Threaded two cores, but its weakness against Intel’s Core processors have always been their single- and lightly-threaded performance. And with the recent release of Intel’s Sandy Bridge i5 2500K and i5 2600K, the performance gap has widened in Intel’s favor.

We are going to be looking to see what AMD has done to close the price-to-performance gap by pricing its top still-current generation Phenom II quads against the newer Core-i3s and we shall again attempt to determine value for PC gamers – from entry level gaming to beyond upper-midrange with the GTX 580.

Head over to the next page and we’ll find more out about the Core i3 architecture and Hyper-Threading.