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Review: Intel's Core i7-3770K 'Ivy Bridge' processor

Progress of a different sort

Yes, folks, today Intel is introducing the long-anticipated new CPU code-named Ivy Bridge. The release of any new microprocessor comes with a tremendous amount of complex information, and Ivy is certainly no exception. Intel has handed over vast amounts of detail about its new chip, the products based on it, and their dizzying arrays of features. To that, we've added a boatload of test results comparing Ivy Bridge to her contemporaries. We're practically bursting with info to share with you.

However, I've been reviewing CPUs for quite a while now, and I'll let you in on a little secret. Sometimes, beneath all of the complexity, the scuttlebutt on a new chip is pretty simple. And, truth be told, that's pretty much the case with Ivy Bridge. This new CPU is an incremental refinement of Sandy Bridge; its benefits are a slight jump in performance and a somewhat larger reduction in power consumption.

I'm oversimplifying, of course. The changes to Ivy Bridge's integrated graphics are sweeping, for example, and there are a multitude of other tweaks worthy of note. Still, I see no reason not to give you the simple answer up front. Much of what follows is our attempt to distill a vast amount of information about Ivy Bridge down to the most relevant details and then to poke and prod this new chip to see how it compares. Because, you know, that's what we do. We've had Ivy Bridge on the test bench here in Damage Labs for some time now, and we've focused most of our efforts on devising—and executing—new methods of testing CPUs. Ivy has been an intriguing test subject, and we hope to show you some things about her that you won't learn anywhere else.

Into Ivy
Ivy Bridge comes into life with every advantage, because it is derived from Intel's excellent Sandy Bridge processor. Ivy is a "tick" in Intel's vaunted tick-tock development cadence, a familiar architecture ported to a new, smaller chip fabrication process. Thus, Ivy looks very much like her older sister in terms of overall layout; they both have quad CPU cores, 8MB of last-level cache, integrated graphics, and built-in PCI Express connectivity, all tied together by a high-speed communications ring. Ivy Bridge processors will drop into the same LGA1155 socket as Sandy Bridge CPUs, in fact.

The biggest change here is the transition from a 32-nm fab process with Sandy to a 22-nm process for Ivy. Don't zone out when you hear those words, folks. This conversion is not at all trivial, even though Intel has made regular work of transitioning to new fabrication processes every couple of years. The drum-beat of Moore's Law has continued apace only because Intel and others have sunk billions into the development of new chipmaking techniques, and these transitions are getting harder to achieve each time. Those pesky laws of physics are becoming ever more difficult to navigate at the nanometer level, which is why companies like GlobalFoundries (which makes AMD CPUs) and TSMC (which makes GPUs for both AMD and Nvidia) are still struggling to produce enough chips with the right characteristics at the 32/28-nm level. Meanwhile, Intel is at least one full generation ahead by shipping 22-nm Ivy Bridge chips in volume today.

In order to make that happen, the firm has fundamentally rebuilt the transistor using a three-dimensional structure that it calls the tri-gate transistor. Intel has claimed these new transistors offer "up to 37 percent performance increase at low voltage versus Intel's 32nm planar transistors," a property its had said will prove especially useful for "small handheld devices" like smart phones, whose low-power chips should be able to operate at considerably higher clock speeds. There's another way to capitalize on the process improvements, too. The new transistors can deliver even larger power savings at the same operating speed as 32-nm chips; the firm has claimed power reductions of over 50% in that case.

These things are well and good, of course, but the trick is how they'll translate into desktop processors like the Core i7-3770K we're reviewing today. The claims cited above were expressly made about operation at relatively low voltages and clock speeds compared to those of current desktop CPUs. At clock speeds approaching 4GHz and their accompanying voltage levels, the advantages offered by Intel's 22-nm process are more modest. Desktop CPUs are probably approaching the hairy end of the frequency-voltage curve for 22-nm chips, where exponential growth in power consumption really begins to ramp up. That reality, perhaps combined with the changing dynamics of the PC market, appears to have driven Intel to make an unusual decision with Ivy Bridge: to realize 22-nm process tech improvements in the form of power reductions, not speed increases, for its desktop processors. Rather than rolling out a bunch of new CPU models with higher clock speeds in the traditional power bands, Intel has elected to reduce desktop power envelopes and hold clock speeds more or less steady.

In fact, the Core i7-3770K's basic CPU clocks and specs are very close to those of the Core i7-2600K introduced in January 2011. The 3770K's base and Turbo clocks are 100MHz higher, just like the 2700K model released last October. Prices have largely held steady, too. The 2600K's introductory price was $317, and it hasn't dropped over the course of the past 16 months. The 3770K supplants it for $5 less. The only truly dramatic change is the reduction in TDP, from 95W for the top Sandy Bridge chips to 77W for their Ivy-based replacements.

This move will have some positive impacts, of course, but they're not exactly the sort of price-performance gains that have made PC enthusiasts swoon in the past. Will folks be excited by claims like "reduced cubic volumes for desktop enclosures" or "easier integration into all-in-one systems?" I'm having a hard time imagining the banner ads. Of course, everything Intel is doing with Ivy Bridge makes a tremendous amount of sense for laptops and other types of mobile devices, which is where much of the PC market is headed.

Code name Key
Cores Threads Last-level
cache size
Process node
Lynnfield Core i5, i7 4 8 8 MB 45 774 296
Gulftown Core i7-970, 990X 6 12 12 MB 32 1168 248
Sandy Bridge Core i5, i7 4 8 8 MB 32 995 216
Sandy Bridge-E Core-i7-39xx 8 16 20 MB 32 2270 435
Ivy Bridge Core i5, i7 4 8 8 MB 22 1400 160
Deneb Phenom II 4 4 6 MB 45 758 258
Thuban Phenom II X6 6 6 6 MB 45 904 346
Llano A8, A6, A4 4 4 1 MB x 4 32 1450 228
Orochi/Zambezi FX 8 8 8 MB 32 1200 315

One bit of good news for somebody, whether it's Intel shareholders or eventually consumers, is that Ivy Bridge should be very affordable to produce once Intel's 22-nm process matures. At 160 mm² for the quad-core variant with the beefiest HD 4000 graphics, Ivy Bridge is easily one of the smallest desktop processors in recent years.

A closer look at the numbers above will give you a sense of how far ahead of the competition Intel truly is. It's no secret that you can expect to see Ivy Bridge outperforming the FX-8150 processor, yet Ivy occupies almost half the die area of Zambezi—and Zambezi lacks integrated graphics and PCIe connectivity. The gap in TDPs between the two would be laughable, if it weren't kind of dire. AMD's true competitor in Ivy's weight class is Llano, which has four cores and almost the same transistor budget, yet Llano is a larger chip because it's fabbed on a 32-nm process. Llano's prospects for matching Ivy in CPU performance are similar to my hometown Royals' prospects for winning the A.L. Central.