Intel Ivy Bridge Hybrid Series
Intel’s Ivy Bridge series has been extensively tested already, but we’ve never approached them as APUs. Meanwhile, the introduction of OpenCL 1.1 support on the graphics core is one of the key advantages of this microarchitecture. In fact, the Ivy Bridge can be viewed as Intel’s first generation of hybrid processors. Even though Intel itself shuns this designation, just because the term APU was coined by its competitor, Intel’s modern CPUs have every right to be discussed as APUs next to AMD’s solutions.
Like the Trinity, the Ivy Bridge chip consists of three main components: x86 cores, a graphics core and North Bridge (also known as System Agent). The microarchitecture of the x86 cores, which may number up to four inside one chip, is a next, yet not very big, step ahead in the evolution of Intel’s exclusive Core design. Compared to the previous-generation x86 cores (Sandy Bridge), there are but very few changes which mostly boil down to the transition to 22nm tech process. On the other hand, Intel’s current products are blameless when it comes to conventional computing as they offer much higher performance than their competitors, mostly because Ivy Bridge execution cores are full-featured and self-sufficient units which do not share any functional subunits with their neighbors and can even execute two instruction threads concurrently thanks to the Hyper-Threading technology.
Considering the higher computing capacity of modern Intel CPUs, we will only take dual-core Ivy Bridge products to compare with AMD’s APUs. Their quad-core cousins are fundamentally faster than the Trinity in performance as well as price, so they should be viewed as a separate class of products that are targeted as high-performance computers with discrete graphics cards. By limiting our scope in this way, we do not limit our choice of Intel’s graphics cores: there are all existing Intel HD Graphics modifications available among the dual-core Ivy Bridge CPUs.
That’s most appropriate for our purpose since the new-generation graphics cores implemented in the Ivy Bridge series differ from their predecessors dramatically, making inexpensive LGA1155 CPUs competitive against Trinity APUs. Most importantly, the new HD Graphics is compatible with DirectX 11, OpenGL 3.1 and OpenCL 1.1, so it can work with any modern 3D and computing algorithms. Moreover, Intel has nearly doubled 3D performance in the Ivy Bridge series, incorporating up to 16 execution units with improved bandwidth in the integrated graphics core.
It must be noted, however, that AMD, being the inventor of the APU concept, puts much more emphasis on the 3D capabilities of its processors. In Intel’s design, the graphics core takes about 30% of the total area of the semiconductor chip with four x86 cores whereas in the Trinity design the graphics core takes over 45% of the total area. However, Intel agrees with AMD that modern graphics cores are expected to do something more than just building and outputting images. That’s why the HD Graphics series has been developing in terms of its rendering pipeline as well as in terms of HD video decoding. Intel also offers the Quick Sync technology that supports hardware encoding of video into H.264 format.
The less prominent position of the graphics core in the Ivy Bridge CPU is somewhat compensated by the developer’s increased focus on the CPU-integrated North Bridge. Considering that the performance of an integrated graphics core is often limited by memory bandwidth, it is now connected to the CPU’s common ring bus. Thus, it has the same rights to system memory access as the x86 cores and also makes full use of the fast L3 cache which is an integral part of every high-performance Intel CPU.
For this review we tested four Ivy Bridge modifications that fit into the same price category as the AMD Trinity series. These are junior Core i3 models with different versions of Intel’s integrated graphics (HD Graphics 4000 and HD Graphics 2500) as well as Pentium and Celeron CPUs whose graphics core is called just HD Graphics without any numeral but has the same architecture. Basic specs of these CPUs are listed in the following table:
Now let’s move on from these basics to details.