Saturday, May 7, 2011
Additional Details on Sandy Bridge-E Processors, X79, and LGA2011
The latest Intel roadmap has come out, and it's already being discussed elsewhere, so we're going to weigh in with our own analysis of the content as there's plenty of interesting bits of information to sift through. We’ll be looking at other areas over the coming days, but today we’re going to start with the Sandy Bridge-E (SNB-E) processors.
Sporting a new socket and chipset, the SNB-E CPUs will start showing up in Q4 this year. None of this is new, as we’ve known the general timeframe for the launch since our Sandy Bridge review, but we can now add some concrete specs. According to the roadmap, the initial SNB-E lineup will consist of three CPUs: two hex-core processors and one quad-core. We don’t have model numbers yet, but we do have most of the other pieces of information.
The Sandy Bridge-E Lineup
Family Core i7 Extreme Core i7 Core i7
Core/Thread Count 6/12 6/12 4/8
Frequency 3.3GHz 3.2GHz 3.6GHz
Max SC Turbo 3.9GHz 3.8GHz 3.9GHz
L3 Cache 15MB 12MB 10MB
Overclocking Fully unlocked Fully unlocked Limited unlock
The new chips will all use the LGA2011 socket with Intel’s X79 chipset, scheduled for simultaneous release with the CPUs. The platform replaces the current LGA1366 with X58 chipset, providing an upgrade path for high-end enthusiasts and workstation users. Memory support will move up to quad-channel DDR3-1333, so where the current Bloomfield can provide up to 25.6GB/s of bandwidth at the specified tri-channel DDR3-1066, LGA2011 kicks that figure up to 42.7GB/s—a 66% increase. The additional memory bandwidth should be particularly useful with certain workloads on the hex-core chips.
One interesting piece of information is that the roadmaps make no mention of integrated graphics or Quick Sync, suggesting the platform will be for discrete graphics only. That makes perfect sense on one level, as users likely to upgrade to such high-end systems are almost sure to have discrete GPUs. On the other hand, Quick Sync has proven very effective for video transcoding, providing up to a four-fold increase over CPU-based encoding, so the loss of the feature is unfortunate.
Intel hasn’t disclosed all of the various Turbo modes yet, but they have listed the maximum single-core Turbo speeds. Both the hex-core 3.3GHz and quad-core 3.6GHz top out at a maximum speed of 3.9GHz, and likely the hex-core chip can do 3.6GHz on QC workloads making it equal to or better than the QC chip on every potential workload. The 3.2GHz hex-core steps the maximum clocks speeds down 100MHz, along with cutting the L3 cache size. As with other i7 processors, all the new chips support Hyper-Threading, and while the hex-core chips will be fully multiplier unlocked the quad-core offering will be a “limited unlock”. The roadmap states that the limited unlock will allow up to six bins of overclocking above the maximum Turbo frequencies, which means that even that chip should be able to hit up to 4.5GHz (with appropriate cooling, motherboard, etc.)
Intel makes no mention of pricing at this time, but the new chips should follow familiar patterns. The i7 Extreme will replace the current i7-990X and target the familiar $1000 price point. Moving down, the 3.2GHz hex-core replaces the current i7-980 (which is set to replace the i7-970 in the near future), taking over the $550~$600 range. At the bottom of the SNB-E lineup is the quad-core 3.6GHz chip, which will take over from the i7-960 as well as providing a competitor to the i7-2600 in the sub-$300 market.
Processor Support LGA1366 LGA2011
PCIe Graphics 2x16 or 4x8 (chipset) 2x16 or 4x8 (CPU)
PCIe Based Uplink to CPU for Storage No Yes (x4)
USB 2.0 Ports 12 14
SATA Total (6Gbps) 6 (0) 14 (10)
One final area to discuss is the chipset. We’ve included X58 in the above table as a reference point, and we can see that X79 improves a few areas but still fails to support a few newer technologies. While the X79 chipset will include native support for SATA 6Gbps (up to 10 ports, with four additional SATA 3Gbps ports), USB 3.0 support is still missing, similar to the current 5- and 6-series chipsets. X79 natively supports dual x16 PCIe graphics, or quad x8 graphics, but this time the PCIe lanes come directly from the CPU instead of from the chipset, providing lower latency GPU access. There’s another extra, as the CPU (chipset) has the option to use four additional PCIe lanes from the PCH dedicated to storage bandwidth, presumably to help with performance on fast SATA 6Gbps devices (e.g. SSDs).
Given the 2x16 PCIe lanes for graphics and quad-channel memory, we can account for most of the pinout increase relative to LGA1366 and LGA1155, and adding in these remaining storage PCIe lanes with a DMI link to the chipset should take care of the rest. Intel doesn't state whether they're using DMI or QPI, but DMI 2.0 only provides up to 20Gbps between the CPU and chipset, so supporting 10 SATA 6Gbps ports with fast SSDs would certainly saturate that.
That wraps up the consumer side of the SNB-E platform. Note that Intel will also have SNB-E Xeons launching in a similar timeframe. The bigger concern for us is that SNB-E continues the strengths of the Bloomfield/Gulftown processors but doesn’t address some of the weaknesses (i.e. lack of Quick Sync). SNB-E looks like a very capable processor, but if you’re willing to forego the current SNB lineup and wait for SNB-E, you’ll then have to contend with Ivy Bridge. That will be Intel’s first 22nm CPU and it’s scheduled for release in the first half of 2012, but that’s a story for a separate article. We’ll also have additional information on Atom CPUs and Intel SSDs in the near future.