The most impressive feature of Intel's new Ivy Bridge CPU is the graphics portion of the chip. The HD 4000 GPU built into these processors is a huge improvement over the chips found in current-generation Sandy Bridge products, and is fast enough to make inexpensive entry-level graphics cards obsolete. You'll still want a good discrete graphics cards for serious gaming, but our benchmarks show that there's just no reason to buy a $50 graphics card anymore.
This stands in contrast to the processor's general compute performance, which is just slightly faster than current Intel CPUs. (For more, take a look at our testing of overall Ivy Bridge performance.) Ivy Bridge is more energy-efficient, which will be especially useful in laptops, but the most noticeable change in performance will be felt when you run 3D graphics applications.
Features, Speeds, and Feeds
At first blush the Ivy Bridge GPU might seem as if it would run slower than the Intel HD 3000 technology built into Intel's Sandy Bridge processors. The Sandy Bridge GPU runs at a base clock frequency of 850MHz, with a Turbo Boost clock as high as 1350MHz. Ivy Bridge’s HD 4000 GPU, on the other hand, is 200MHz slower, operating at a base clock speed of 650MHz, with a Turbo Boost clock of 1150MHz.
Intel has made enhancements to the GPU engine to improve efficiency, but other factors help to mitigate the clock-rate differential, too. First, the new HD 4000 GPU contains 16 execution units, versus the 12 built into Sandy Bridge. Second, Ivy Bridge supports DDR3-1600 memory, as opposed to the Sandy Bridge memory controller, which officially supports only DDR3-1333. Ivy Bridge gains 25 percent more parallel compute power and higher potential throughput due to the added memory bandwidth.
Before diving into performance comparisons, it’s worthwhile to examine additional Ivy Bridge GPU feature changes.
- Full support for Microsoft’s DirectX 11 API, including hardware tessellation and GPU compute: Intel claims that GPU-compute applications will run exclusively on the Ivy Bridge GPU if so instructed, and GPU-compute tasks won't be offloaded to the CPU.
- Two texture units are present, as opposed to a single texture unit in Sandy Bridge.
- The new compute shader enables greater data parallelism, and full support for Shader Model 5, which is required for DirectX 11.
- A shared L3 cache is built into the GPU core itself, which reduces the need to fetch data from the ring bus and the CPU cache.
- Support is included for up to three simultaneous displays (DVI, HDMI, or DisplayPort).
- HDMI 1.4a, including high-bit-rate audio, is supported.
- Quick Sync video is improved, and includes better support for Blu-ray stereoscopic 3D.
Those feature additions, along with the internal rearchitecting of the actual compute units, suggest that Ivy Bridge 3D graphics performance should be better than what you can get from other products. Let’s take a look at actual benchmarks.
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