The Sandy Bridge Previewby Anand Lal Shimpi on August 27, 2010 2:38 PM EST
A New Architecture
This is a first. Usually when we go into these performance previews we’re aware of the architecture we’re reviewing, all we’re missing are the intimate details of how well it performs. This was the case for Conroe, Nehalem and Lynnfield (we sat Westmere out until final hardware was ready). Sandy Bridge, is a different story entirely.
Here’s what we do know.
Sandy Bridge is a 32nm CPU with an on-die GPU. While Clarkdale/Arrandale have a 45nm GPU on package, Sandy Bridge moves the GPU transistors on die. Not only is the GPU on die but it shares the L3 cache of the CPU.
There are two different GPU configurations, referred to internally as 1 core or 2 cores. A single GPU core in this case refers to 6 EUs, Intel’s graphics processor equivalent (NVIDIA would call them CUDA cores). Sandy Bridge will be offered in configurations with 6 or 12 EUs.
While the numbers may not sound like much, the Sandy Bridge GPU is significantly redesigned compared to what’s out currently. Intel already announced a ~2x performance improvement compared to Clarkdale/Arrandale, and I can say that after testing Sandy Bridge Intel has been able to achieve at least that.
Both the CPU and GPU on SB will be able to turbo independently of one another. If you’re playing a game that uses more GPU than CPU, the CPU may run at stock speed (or lower) and the GPU can use the additional thermal headroom to clock up. The same applies in reverse if you’re running something computationally intensive.
On the CPU side little is known about the execution pipeline. Sandy Bridge enables support for AVX instructions, just like Bulldozer. The CPU will also have dedicated hardware video transcoding hardware to fend off advances by GPUs in the transcoding space.
Caches remain mostly unchanged. The L1 cache is still 64KB (32KB instruction + 32KB data) and the L2 is still a low latency 256KB. I measured both as still 4 and 10 cycles respectively. The L3 cache has changed however.
Only the Core i7 2600 has an 8MB L3 cache, the 2400, 2500 and 2600 have a 6MB L3 and the 2100 has a 3MB L3. The L3 size should matter more with Sandy Bridge due to the fact that it’s shared by the GPU in those cases where the integrated graphics is active. I am a bit puzzled why Intel strayed from the steadfast 2MB L3 per core Nehalem’s lead architect wanted to commit to. I guess I’ll find out more from him at IDF :)
The other change appears to either be L3 cache latency or prefetcher aggressiveness, or both. Although most third party tools don’t accurately measure L3 latency they can usually give you a rough idea of latency changes between similar architectures. In this case I turned to cachemem which reported Sandy Bridge’s L3 latency as 26 cycles, down from ~35 in Lynnfield (Lynnfield’s actual L3 latency is 42 clocks).
As I mentioned before, I’m not sure whether this is the result of a lower latency L3 cache or more aggressive prefetchers, or both. I had limited time with the system and was unfortunately unable to do much more.
And that’s about it. I can fit everything I know about Sandy Bridge onto a single page and even then it’s not telling us much. We’ll certainly find out more at IDF next month. What I will say is this: Sandy Bridge is not a minor update. As you’ll soon see, the performance improvements the CPU will offer across the board will make most anyone want to upgrade.
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foundchild1 - Friday, August 27, 2010 - link"For example, today the fastest LGA-1156 processor is the Core i7 880. When Sandy Bridge launches early next year, the fastest LGA-1155 processor will be the Core i7 2600."
Shouldn't the second one also read LGA-1156? Are they changing the pin count/socket for this 'tock'?
foundchild1 - Friday, August 27, 2010 - linkWell, that's me being an idiot and not reading the whole article first... New socket indeed.
medi01 - Saturday, August 28, 2010 - linkSo intel has locked multtipliers because of some other evil companies, eh? To protect the consumers, right?
What a shame... :(
jfelano - Sunday, August 29, 2010 - linkDid you even read the article???? Yes its s1155.
wazzap123 - Thursday, November 18, 2010 - linkThe story of how caches are going to work in the 8+ core world is getting exciting. I like the overview at the daily circuit that summarizes how Niagara 3, Tilera Gx-100, and BlueGene/P processors weigh in on the issue too
dendysutrisna - Friday, August 12, 2011 - linkThe Apple iMac 21.5inch is a computer machine which uses the power of Intel Core i5-2400. Look at these page: http://www.bestdealscomputers.net/desktops/new-app... Processors like that, thanks to its strength, could draw the attention of everyone, even computer vendors at the level Apple also has without a doubt to hook them.
Grooveriding - Friday, August 27, 2010 - linkIt's hard to wade through all this data so quickly. That said, as far as overclocking, the new 2011 socket will be the successor to 1366 ?
I hope with all these new overclocking controls there will still be that mainstay $300 CPU that can overclock to some extreme performance. Meaning a successor to the i7 920/930 that can deliver the amazing performance those can overclocked.
I hope this is not the death knell for such a CPU and Intel is expecting us to fork over $1000 for that performance level.
BSMonitor - Friday, August 27, 2010 - linkGood question, but judging by the road map, the Extreme and Performance segments are still Gulftown Processors. I think the 1366 stays for Gulftown.
Casper42 - Saturday, August 28, 2010 - linkOn the 2P Server side of things, I have been told there will be a Westmere v2 coming in January 2011.
This is probably the same family that will produce the i7 990 and the other 1366 chips on the chart that don't exist yet. The Xeon 5600 and 970/980 are damn near identical aside from QPI Links.
Being those are being released in Jan, I wouldn't expect to see a socket 2011 desktop part until basically a year from now.
They will once again be a close relative to the 2P Server family. The socket for the 2P Servers will be Socket R and will be Quad Channel memory as well as supposedly having PCIe 3.0.
bitzao - Friday, August 27, 2010 - linkYeah but.... will it run Starcraft II ? (on medium)