The Sandy Bridge Review: Intel Core i7-2600K, i5-2500K and Core i3-2100 Testedby Anand Lal Shimpi on January 3, 2011 12:01 AM EST
Intel never quite reached 4GHz with the Pentium 4. Despite being on a dedicated quest for gigahertz the company stopped short and the best we ever got was 3.8GHz. Within a year the clock (no pun intended) was reset and we were all running Core 2 Duos at under 3GHz. With each subsequent generation Intel inched those clock speeds higher, but preferred to gain performance through efficiency rather than frequency.
Today, Intel quietly finishes what it started nearly a decade ago. When running a single threaded application, the Core i7-2600K will power gate three of its four cores and turbo the fourth core as high as 3.8GHz. Even with two cores active, the 32nm chip can run them both up to 3.7GHz. The only thing keeping us from 4GHz is a lack of competition to be honest. Relying on single-click motherboard auto-overclocking alone, the 2600K is easily at 4.4GHz. For those of you who want more, 4.6-4.8GHz is within reason. All on air, without any exotic cooling.
Unlike Lynnfield, Sandy Bridge isn’t just about turbo (although Sandy Bridge’s turbo modes are quite awesome). Architecturally it’s the biggest change we’ve seen since Conroe, although looking at a high level block diagram you wouldn’t be able to tell. Architecture width hasn’t changed, but internally SNB features a complete redesign of the Out of Order execution engine, a more efficient front end (courtesy of the decoded µop cache) and a very high bandwidth ring bus. The L3 cache is also lower and the memory controller is much faster. I’ve gone through the architectural improvements in detail here. The end result is better performance all around. For the same money as you would’ve spent last year, you can expect anywhere from 10-50% more performance in existing applications and games from Sandy Bridge.
I mentioned Lynnfield because the performance mainstream quad-core segment hasn’t seen an update from Intel since its introduction in 2009. Sandy Bridge is here to fix that. The architecture will be available, at least initially, in both dual and quad-core flavors for mobile and desktop (our full look at mobile Sandy Bridge is here). By the end of the year we’ll have a six core version as well for the high-end desktop market, not to mention countless Xeon branded SKUs for servers.
The quad-core desktop Sandy Bridge die clocks in at 995 million transistors. We’ll have to wait for Ivy Bridge to break a billion in the mainstream. Encompassed within that transistor count are 114 million transistors dedicated to what Intel now calls Processor Graphics. Internally it’s referred to as the Gen 6.0 Processor Graphics Controller or GT for short. This is a DX10 graphics core that shares little in common with its predecessor. Like the SNB CPU architecture, the GT core architecture has been revamped and optimized to increase IPC. As we mentioned in our Sandy Bridge Preview article, Intel’s new integrated graphics is enough to make $40-$50 discrete GPUs redundant. For the first time since the i740, Intel is taking 3D graphics performance seriously.
|CPU Specification Comparison|
|CPU||Manufacturing Process||Cores||Transistor Count||Die Size|
|AMD Thuban 6C||45nm||6||904M||346mm2|
|AMD Deneb 4C||45nm||4||758M||258mm2|
|Intel Gulftown 6C||32nm||6||1.17B||240mm2|
|Intel Nehalem/Bloomfield 4C||45nm||4||731M||263mm2|
|Intel Sandy Bridge 4C||32nm||4||995M||216mm2|
|Intel Lynnfield 4C||45nm||4||774M||296mm2|
|Intel Clarkdale 2C||32nm||2||384M||81mm2|
|Intel Sandy Bridge 2C (GT1)||32nm||2||504M||131mm2|
|Intel Sandy Bridge 2C (GT2)||32nm||2||624M||149mm2|
It’s not all about hardware either. Game testing and driver validation actually has real money behind it at Intel. We’ll see how this progresses over time, but graphics at Intel today very different than it has ever been.
Despite the heavy spending on an on-die GPU, the focus of Sandy Bridge is still improving CPU performance: each core requires 55 million transistors. A complete quad-core Sandy Bridge die measures 216mm2, only 2mm2 larger than the old Core 2 Quad 9000 series (but much, much faster).
As a concession to advancements in GPU computing rather than build SNB’s GPU into a general purpose compute monster Intel outfitted the chip with a small amount of fixed function hardware to enable hardware video transcoding. The marketing folks at Intel call this Quick Sync technology. And for the first time I’ll say that the marketing name doesn’t do the technology justice: Quick Sync puts all previous attempts at GPU accelerated video transcoding to shame. It’s that fast.
There’s also the overclocking controversy. Sandy Bridge is all about integration and thus the clock generator has been moved off of the motherboard and on to the chipset, where its frequency is almost completely locked. BCLK overclocking is dead. Thankfully for some of the chips we care about, Intel will offer fully unlocked versions for the enthusiast community. And these are likely the ones you’ll want to buy. Here’s a preview of what’s to come:
The lower end chips are fully locked. We had difficulty recommending most of the Clarkdale lineup and I wouldn’t be surprised if we have that same problem going forward at the very low-end of the SNB family. AMD will be free to compete for marketshare down there just as it is today.
With the CPU comes a new platform as well. In order to maintain its healthy profit margins Intel breaks backwards compatibility (and thus avoids validation) with existing LGA-1156 motherboards, Sandy Bridge requires a new LGA-1155 motherboard equipped with a 6-series chipset. You can re-use your old heatsinks however.
Clarkdale (left) vs. Sandy Bridge (right)
The new chipset brings 6Gbps SATA support (2 ports) but still no native USB 3.0. That’ll be a 2012 thing it seems.
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IanWorthington - Monday, January 3, 2011 - linkNot really: the board manufacturers seem to be adding usb3 chipsets w/o real problems. Good enough.
usernamehere - Monday, January 3, 2011 - linkSure, if you're building a desktop you can find plenty with USB 3.0 support (via NEC). But if you're looking for a laptop, most will still not have it. For the fact that manufacturers don't want to have to pay extra for features, when they usually get features via the chipsets already included. Asus is coming out with a handful of notebooks in 2011 with USB 3.0 (that I know of), but wide-spread adoption will not be here this year.
JarredWalton - Monday, January 3, 2011 - linkMost decent laptops will have USB3. ASUS, Dell, HP, Clevo, and Compal have all used the NEC chip (and probably others as well). Low-end laptops won't get USB3, but then low-end laptops don't get a lot of things.
TekDemon - Monday, January 3, 2011 - linkEven the netbooks usually have USB 3.0 these days and those almost all use intel atom CPUs. The cost to add the controller is negligible for large manufacturers. USB is not going to be the deciding factor for purchases.
DanNeely - Monday, January 3, 2011 - linkAre you sure about that? Newegg lists 99 netbooks on their site. Searching for USB 3 within netbooks returns 0 products.
TekDemon - Monday, January 3, 2011 - linkYour claims are pretty silly seeing as how USB came about in the same way that Light Peak did-Intel invented USB and pushed it to legacy ports like PS/2, and slowly phased out support for the older ones entirely over the years. It makes no sense for them to support USB 3.0, especially without a real market of devices.
But motherboard manufacturers will support USB 3.0 via add-in chips. I don't see how this anti-competitive at all, why should intel have to support a format it doesn't think makes sense? So far USB 3.0 hasn't really shown speeds close to it's theoretical, and the only devices that really need the higher bandwidth are external drives that are better off being run off E-SATA anyways. There's no real "killer app" for USB 3.0 yet.
BTW Light Peak will easily support adding power to devices, so it definitely does not need USB in order to provide power. There'll just be two wires running alongside the fiber optics.
DanNeely - Tuesday, January 4, 2011 - linkThe eSata + USB (power) connector has never gone anywhere, which means that eSata devices need at least 2 cables to work. Flash drives and 2.5" HDs don't need enough power to require an external brick, and 80-90% of eSata speed is still much better than the USB2 bottleneck. With double the amount of power over USB2, USB3 could theoretically be used to run 3.5" drives with a double socket plug freeing them from the wall as well.
ilkhan - Monday, January 3, 2011 - linkI've had my P67A-UD4 for almost 3 weeks now. Lets get the chips out already!
I'm confused, however. The fist paragraph talks of 4.1Ghz turbo mode and the chart on page 2 lists 3.8Ghz as the max for the 2600K. Is the chart talking about 4-core turbo or what?
Spike - Monday, January 3, 2011 - linkIsn't it an i7-2600k? The article title says "i5 2600k"... just curious...
Ryan Smith - Monday, January 3, 2011 - linkOh dear...
Fixed. Thanks for that.