Quick Analysis: Nehalem CPUs & Sockets

Wednesday 05th December 2007, 10:45:00 PM, written by Arun

There remains a significant amount of confusion on the derivatives based on Intel's upcoming Nehalem microarchitecture. A week ago, PC Watch released an article in Japanese on upcoming desktop sockets and CPUs, but it didn't collide perfect with previous rumours and many websites reporting on the news seemed, at best, horribly confused.

So based on our own analysis (and speculation) of existing information, we try to clarify what the actual products will be, and what it will mean for other companies.

Sockets

• Socket 1366: 3xDDR3, External PCI Express, 1-2xQuickPath (Optional 2S?), Q408.
• Socket 1160: 2xDDR3, 16xPCI Express Gen2, DMI (to southbridge, slower than FSB), 1H09.
• Socket 715: No IMC, Optional PCI Express, 1xQuickPath to northbridge, 1H09.

Desktop CPUs

• Bloomfield: Socket 1366, Quad-Core, Ultra-High-End.
• Lynnfield: Socket 1160, Quad-Core, High-End.
• Havendale: Socket 1160, MCM (CPU+GPU/IMC), Dual-Core, Mid-Range.
• ?Havendale?: Socket 715, Dual-Core, Low-End. Northbridges can use DDR2.

Chipsets

• Socket 1366: Northbridge (PCI Express) + ICHx Southbridge (I/O).
• Socket 1160: Single-Chip Southbridge (I/O) aka Ibexpeak PCH.
• Socket 715: NVIDIA: Single-Chip, Intel/SiS: ???

Note: The following per-socket consequences are *not* supposed to be as clear/concise as the above, and may even list some fairly trivial data; they are semi-extensive lists for those interested in such things (future chipsets, business consequences, etc.) - if you don't care about that or don't like the presentation, don't read it, period.

Consequences: Socket 1366

• Intel is expected to use a new northbridge (Tylersburg) for this market, which will connect to ICHx. Some SKUs will support 2x16 PCI Express Gen2, others 3x8. It is unclear if these are different chips or not, but either way xtreview.com has nice diagrams of them all.
• NVIDIA will certainly need a new chip for this market. One possibility is a PCI Express bridge chip which also includes 1xDMI, 1xHT3 (for 2S) and 1xQuickPath.
• The GPU for Hybrid SLI could either be integrated or remain on the southbridge. If it did have an IGP, it could also be sold to Intel and motherboard manufacturers as a 'bridge chip with Hybrid SLI'.
• NVIDIA doesn't really need a chipset for Nehalem's launch as long as Intel is willing to support BR04.
• Obviously, SiS is unlikely to be interested in making chipsets for this ultra-high-end socket.

Consequences: Socket 1160

• Display Connect on S1160 is where it gets a bit iffy: to keep the same socket as no-GPU packages, the display interfaces are external. So that will likely be optional and not all Intel ICHs will support it, which means some motherboards won't support on-package GPUs (but will still be upgradable to quad-cores).
• All of this is also positive for SiS, as they will now be able to sell super-cheap non-IGP southbridges on S1160, a market neither Intel nor NVIDIA seem to be very interested in.
• It should be possible for NVIDIA to reuse their HT3 chipsets with an extra DMI interconnect here, which is probably extremely cheap. The Display Connection also shouldn't be too hard (just disable the IGP and keep the outputs). However, there is one problem: Hybrid SLI.
• The solution for non-SLI chipsets could be that Lynnfield has two PCI Express links, so you might connect that to both the chipset and an external port. For SLI chipsets, they'll need a BR04-like bridge chip unless Intel was nice enough to add support for 3 links.
• NVIDIA will probably also need a 'plain' chip without an integrated GPU or 16x PCI Express for Socket 1160 to be cost-competitive in certain markets. If the S1366 northbridge had an IGP, this chip could also be used as a southbridge there, and that 'northbridge' could be used as a Hybrid SLI bridge chip on S1160.

Consequences: Socket 715

• S715 will probably need new chipsets for all three companies (Intel/NVIDIA/SiS). The only major question is whether Intel and SiS will migrate to single-chip solutions like NV.
• Penryn will likely remain important for the dual-core segment in 2009. Also, S715 is unlikely to die in the 32nm generation, although its importance in terms of shipment volume is hard to predict.
• From a marketing perspective, it seems plausible that all chips for this lower-end socket will be Pentiums or Celerons.
• As a reminder, VIA's license for Intel sockets will expire in March 2008, so they obviously won't compete here.

While Intel's sockets may be confusing at first, they make a fair bit of sense once you've had the time to think about them. While the different sockets may seem to hurt upgradability, they are clearly aimed at different markets and upgradability inside Socket 1160 (the most important one) is decent.

It is certainly true that Bloomfield's bandwidth is astonishingly high; Penryn will be maxed on single-channel DDR3 @ 1333MHz due to the FSB limitations, but Lynnfield and Bloomfield can achieve 2 and 3 times that, respectively.

It remains to be seen how much that will affect performance (and pricing), but from a platform perspective there's not much to complain about here. It will also be interesting to see what AMD comes up with in that same timeframe, as Bulldozer is still expected to be ready by mid-2009.

Discuss on the forums

intel ± nehalem, nvidia, sis

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