Intel's Ivy Bridge: The Maximum PC Review

Posted 04/24/2012 at 11:24am | by Gordon Mah Ung

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7-series Chipset Brings Few Changes 

 Gigabyte’s GA-Z77X-UD5H features out-of-the-box Ivy Bridge support and USB 3.0 ports powered by Intel!

Conspiracy theorists, unite: If you’re one of the tin-foil hat wearers (this means you, Nathan Edwards) who was absolutely certain Intel was trying to sandbag USB 3.0 in order to push Thunderbolt, the new Z77 chipset puts your suspicions to rest. The Z77, you see, finally brings native USB 3.0 support to the world of Intel. Why all the fuss over native support? First, it cuts the cost of a board, slightly, since the board maker has one less chip to supply. Generally, performance and compatibility of integrated USB 3.0 tends to be better, too. Finally, native support means USB 3.0 in just about every new PC going forward. That means more devices and lower costs, which, as Admiral Kirk says, is better for me, better for you, and (pause) better for them.

Native USB 3.0 won’t extend to all ports on a motherboard, though. The Intel PCH supports up to four USB 3.0 ports, so on motherboards that offer more than that, it’ll be a mix of USB 2.0, Intel USB 3.0, and third-party USB 3.0 support. On the Gigabyte GA-Z77X-UD5H that we used, for example, it had four USB 3.0 ports on back with an additional three USB 3.0 headers. This was done by using the Intel chipset support and a discrete controller from VIA.

Beyond USB 3.0, the 7-series chipsets is a fairly incremental update. SATA support, for example, is the same weak-sauce mix of two SATA 6Gb/s and four SATA 3Gb/s. When we critically asked why not all 6Gb/s ports? Intel threw it back in our face by saying that backward compatibility with the 6-series boards was important to keep costs down on the 7-series boards. And since we’re always whining about backward compatibility, isn’t that important? Well, yes—but this is the last time, Intel. The 5-series, 6-series, and now 7-series have all shared the same SATA 6Gb/s configuration, so we better not see the 8-series with it, too.

Other key differences between 7-series and 6-series are support for three displays using Ivy Bridge’s graphics chip, and of course, support for both Sandy Bridge and Ivy Bridge chips out of the box. Is there a performance difference? Frankly, no. For our tests, we used a Gigabyte GA-Z77X-UD5H board, first with the Core i7-3770K, which we then swapped out for a Core i7-2600K. We then re-ran our benchmarks and compared them to our Z68/2600K numbers. The difference? Nada, other than the weird, unexplainable bogies we had with a couple of benchmarks. The two, frankly, are essentially indistinguishable. Even the Intel USB 3.0 support didn’t prove to be superior to any of the discrete USB 3.0 chipsets we’ve seen. So if you’re considering whether to move from Z68 just to upgrade, we don’t recommend it. However, if you’re building a new box on an Ivy Bridge processor, we’d build on Z77 just to have the latest chipset.

Ivy Bridge Graphics

It’s what everyone’s been waiting for. Does Intel deliver?

We’re all Charlie Browns when it comes to Intel graphics. Intel, of course, is Lucy, pulling the graphics eye-candy football away after promising that this time will be different. Once again, Intel is promising that this generation of the GPU built into the upcoming Ivy Bridge 22nm CPU will be different. Honest!

Several years ago, Intel promised to speed up its graphics core by 10x per generation—and that 10x speedup would start with Ivy Bridge. With Ivy Bridge almost upon us, it’s worth diving in to its internal architecture to understand what’s really changed.

Based on what we know about DirectX 11 compute shaders and the OpenCL 1.1 implementation, it looks like Intel’s new GPU is getting a pretty robust set of compute-capable shaders. That’s an encouraging sign, as is support for hardware tessellation.

Those are the gross differences. Internally, the GPU has been redesigned from the ground up. The GPU is partitioned into five domains. The global asset area takes care of geometry. It includes geometry, vertex, and hull shaders, plus the tessellator. Setup is also in this section. The resulting output is fed into the thread dispatch engine to the execution units (EUs), which do a lot of the heavy lifting. After the EUs are done, the render section takes over.

Intel’s hardware tessellation engine is fixed-function, but can accept different cues for setting the overall level of tessellation. The EUs have been beefed up, with each EU offering 2x the performance per watt of Sandy Bridge. The higher-end HD 4000 has 16 EUs, up from 12 on Sandy Bridge’s GPU. Intel also added an L3 cache to the GPU, which improves overall throughput, since data doesn’t need to be fed to the GPU from the ring bus as frequently. This also saves on overall power.

One of the key performance-enhancing features is co-issue of instructions to execution units. Sandy Bridge supported this on some operations, but Ivy Bridge extends this to many more operations. 

How does this affect actual performance with PC games? We ran a few tests on very early drivers. What we saw was definitely encouraging.

Even with early drivers, we’re seeing about a 25 percent or better increase with 3D games. You’ll still need to sacrifice some detail levels, but you’ll get acceptable performance in all but the most bleeding-edge games. Titles like StarCraft II, Civilization V, Modern Warfare 3, and Portal 2 will probably run fine, if you’re willing to dial back resolution, turn off AA, and run at medium or lower detail levels. It’s probably best to steer away from highly demanding titles, though, such as Deus Ex: Human Revolution or The Witcher 2.

Note that 3DMark 2011 actually runs, giving clear evidence that Ivy Bridge is indeed DirectX 11 compliant. That’s not a big score, but the fact of the score is encouraging. As with Sandy Bridge, Ivy Bridge includes a dedicated, fixed-function video encoder. Intel is claiming a nearly 2x encode advantage over Sandy Bridge, but that will depend on the application and workload. We saw only a 6 percent gain over Sandy Bridge when encoding an HD video file for iPhone using CyberLink’s Media Espresso 6.5 (295 seconds for Ivy Bridge versus Sandy Bridge’s 311 seconds.) Encoding performance is likely to be better with stereoscopic content, for example.

Finally, the new GPU, in conjunction with motherboards using Intel’s 7-series chipsets, will support up to three simultaneous displays. As with Sandy Bridge, DVI support will be limited to single link only, but that will only affect a handful of users with older 30-inch monitors. Full bandwidth support for very high resolutions will be available through DisplayPort 1.2 or HDMI 1.4a.

Overall, Ivy Bridge’s graphics are clearly better. Desktop users who are regular PR gamers will definitely want to stick with their favorite discrete graphics card, but owners of Ivy Bridge ultrabooks might be able to get a reasonable gaming fix now—provided the unit is built with the HD 4000. It’s unlikely that the HD 2500 will be much use for gaming. –Loyd Case

Next up: The benchmarks!