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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karlostomy - Thursday, January 6, 2011 - linkwhat the hell is the point of posting gaming scores at resolutions that no one will be playing at?
If i am not mistaken, the grahics cards in the test are:
eVGA GeForce GTX 280 (Vista 64)
ATI Radeon HD 5870 (Windows 7)
MSI GeForce GTX 580 (Windows 7)
So then, with a sandybridge processor, these resolutions are irrelevant.
1080p or above should be standard resolution for modern setup reviews.
Why, Anand, have you posted irrelevant resolutions for the hardware tested?
dananski - Thursday, January 6, 2011 - linkGames are usually limited in fps by the level of graphics, so processor speed doesn't make much of a difference unless you turn the graphics detail right down and use an overkill graphics card. As the point of this page was to review the CPU power, it's more representative to use low resolutions so that the CPU is the limiting factor.
If you did this set of charts for gaming at 2560x1600 with full AA & max quality, all the processors would be stuck at about the same rate because the graphics card is the limiting factor.
I expect Civ 5 would be an exception to this because it has really counter-intuitive performance.
omelet - Tuesday, January 11, 2011 - linkFor almost any game, the resolution will not affect the stress on the CPU. It is no harder for a CPU to play the game at 2560x1600 than it is to play at 1024x768, so to ensure that the benchmark is CPU-limited, low resolutions are chosen.
For instance, the i5 2500k gets ~65fps in the Starcraft test, which is run at 1024x768. The i5 2500k would also be capable of ~65fps at 2560x1600, but your graphics card might not be at that resolution.
Since this is a review for a CPU, not for graphics cards, the lower resolution is used, so we know what the limitation is for just the CPU. If you want to know what resolution you can play at, look at graphics card reviews.
Tom - Sunday, January 30, 2011 - linkWhich is why the tests have limited real world value. Skewing the tests to maximize the cpu differences makes new cpus look impressive, but it doesn't show the reality that the new cpu isn't needed in the real world for most games.
Oyster - Monday, January 3, 2011 - linkMaybe I missed this in the review, Anand, but can you please confirm that SB and SB-E will require quad-channel memory? Additionally, will it be possible to run dual-channel memory on these new motherboards? I guess I want to save money because I already have 8GB of dual-channel RAM :).
Thanks for the great review!
CharonPDX - Monday, January 3, 2011 - linkYou can confirm it from the photos of it only using two DIMMs in photo.
JumpingJack - Monday, January 3, 2011 - linkThis has been discussed in great detail. The i7, i3, and i5 2XXX series is dual channel. The rumor mill is abound with SB-E having quad channel, but I don't recall seen anything official from Intel on this point.
8steve8 - Monday, January 3, 2011 - linkthe K processors have the much better IGP and a variable multiplier, but to use the improved IGP you need an H67 chipset, which doesn't support changing the multiplier?
ViRGE - Monday, January 3, 2011 - linkCPU Multiplier: Yes, H67 cannot change the CPU multiplier
GPU Multiplier: No, even H67 can change the GPU multiplier
mczak - Monday, January 3, 2011 - linkI wonder why though? Is this just officially? I can't really see a good technical reason why CPU OC would work with P67 but not H67 - it is just turbo going up some more steps after all. Maybe board manufacturers can find a way around that?
Or is this not really linked to the chipset but rather if the IGP is enabled (which after all also is linked to turbo)?