Final Words

I see three reasons why you'd want the Core i7 3820:

1. You need PCIe 3.0 today and/or you need more PCIe lanes than a Core i7 2600K can provide,

2. You need tons of memory bandwidth for a particular application,

3. You want a 2600K but you need a platform that can support more memory (32GB+).

If you fall into any of those categories, the 3820 gets the job done. It's easily as fast as the fastest LGA-1155 Sandy Bridge without adding significant power consumption or really being limited on the overclocking side either. The 3820 admittedly targets a niche, but it does so without any real trade offs. If you land outside of the 3820's niche however, you're better served by the 2500/2600K at a lower total platform cost or a 3930K/3960X if you're running a heavily threaded workload and can use the extra cores.

What About Ivy?

By the time the 3820 is available for purchase early next year, Ivy Bridge will be just about a quarter away. For desktop users Ivy Bridge is really only going to bring lower power consumption and a better integrated GPU. If you're seriously considering anything in the SNB-E family, the latter isn't going to matter and the former will be of arguable value. I do expect that we'll see a drop-in upgrade path to IVB-E at some point in early 2013 if you're concerned about platform longevity, although Intel hasn't officially committed to such a thing. It's pretty safe to say that you'll be on your own after IVB-E however, Haswell should be a fairly large departure from IVB-E in a lot of senses.

For everyone else, if you need a desktop system today - the LGA-1155 Sandy Bridge is still a viable option. There's always something better around the corner but I have no issues recommending either that you buy now or you wait for IVB. If you can wait, you'll be getting a cooler CPU with better integrated graphics and faster Quick Sync.

Power Consumption
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  • horangl3e - Thursday, December 29, 2011 - link

    So if a user were to buy two graphics cards, the gtx 580 for example, would it be more beneficial for that user to use the X79 platform instead of the Z68? Currently I believe that the user would have to split between x8 x8 for each graphics card if they used the non X79 platform but with the X79 both cards would be able to use the proper x16 bandwith for both graphics cards right?
  • chizow - Thursday, December 29, 2011 - link

    There's not much benefit when using 2xPCIE 2.0 single-GPU cards with PCIE 2.0 x8 slots. They just don't need that much bandwidth.

    With multi-GPU cards however, that PCIE 2.0 x8 starts to choke them a bit and x16 starts showing its benefits.

    Another thing to keep in mind too is that with X79 (and IB?) they support PCIE 3.0, so with PCIE 3.0 cards, PCIE 3.0 x8 is the equivalent of PCIE 2.0 x16 in terms of bandwidth. Should be beneficial for multi-card solutions especially with multi-GPU cards.

    I'm assuming Ivy Bridge will also be PCIE 3.0 compliant, but if not, X79 might be even more appealing to people looking to buy the next-gen GPU offerings from AMD/Nvidia.

    Also, Anand or anyone else, since the PCIE controllers are on the CPU dies now, is it possible for SB to support PCIE 3.0 as well? Or are they just too different?
  • B3an - Thursday, December 29, 2011 - link

    Sandy Bridge could never support PCI-E 3.0 without a pretty major revision to the CPU's. Even then i'm not sure if the motherboards would actually work with it.

    If i was buying a quad core right now i would actually go for this i7 3820 over a 2500 - 2700K. Simply because it's more future proof for graphics cards. While no card needs more than x16 PCI-E 2.0 right now for games they certainly will in the future. Plus with SNB-E you can run two cards at x16 @ PCI-3.0 speed, but with SB it's only x8 @ 2.0 speed which already takes a slight performance hit with current cards. The graphics upgrade path for SNB-E will last for years to come.
  • Tchamber - Thursday, December 29, 2011 - link

    I have a Gulftown i7, and doesn't it support PCIe at 16x16? I didn't know Intel took a step back with SNB and PCIe lanes for multi GPUs. Do I understand this right?
  • SlyNine - Thursday, December 29, 2011 - link

    I believe with Gulftown the PCI-E Controller is not based on the CPU. Thats why you can get 16x16x8 with them.
  • SlyNine - Thursday, December 29, 2011 - link

    By based of course I mean located.
  • DanNeely - Thursday, December 29, 2011 - link

    LGA1366 supports 32 PCIe 2.0 lanes. That is more than LGA 1155's 16, but LGA 1155 isn't the official successor to 1366 (even if SB is fast enough it's quads beat 1366 hexes on many benches); it's the LGA 1156 replacement and 11556 also only has 16 2.0 lanes. LGA 2011 replaces LGA 1366 (and LGA 1567 on high end Xeons); and is a major PCIe upgrade.
  • dgingeri - Thursday, December 29, 2011 - link

    Actually, the x58 chipset supports 36 lanes from the northbridge and 6 more form the southbridge:

    This allows three slots using x16/x16/x4 with 6 more for expansion devices or x16/x8/x8 with 10 more for expansion devices. (My P6T is the former while my Rampage III Formula is the latter. Yes, I have 2 lga1366 systems, one a server and one a gaming machine.)

    The 40 lanes from the processor and the 8 lanes from the chipset will be a big boost for using certain devices. I'll be able to run both my video cards at x16 while still using my 10Gbe and LSI RAID cards with x8 slots. :)
  • chizow - Thursday, December 29, 2011 - link

    SNB/P67/Z68 was the successor to the short-lived Lynnfield/Clarkdale P55-based platforms.

    SB-E/X79 is the direct successor to Nehalem/Gulftown/X58.

    Intel has just had the luxury of pushing back the release dates of their parts because no matter what they sell, its faster than AMD and still netting them boatloads of cash.

    So yes, for some time Intel's leading CPUs have been behind on the platform side of things, SB-E settles the balance and represents an upgrade over Nehalem in every aspect.

    This will change again however with IVB, which will be on a smaller process node and probably swing the clockspeed, Turbo, overclocking, and power consumption considerations back in favor of the weaker P67/Z68 platform.

    The main difference however is that IVB will also support PCIE 3.0 so the fewer PCIE lanes will be less of a disadvantage on cards that support PCIE 3.0 when used in multi-GPU configs.
  • Kevin G - Thursday, December 29, 2011 - link

    Ivy Bridge will be supported on current socket 1155 motherboards. It'll bring PCI-E 3.0 but currently motherboards are going to be hit or miss if they support that speed. Intel won't officially support PCI-E 3.0 withe P67/Z68 (and related) chipsets but motherboard manufacturers can take that burden if they choose.

    The main reason to go with socket 2011 isn't a single GPU but rather running multiple GPU's that'll need that bandwidth. For gaming, the performance difference is only a few percentage points. For GPGPU, the difference is greater but if that is the target market, then using a multi-socket 2011 motherboard populated with Xeons is more likely. That'd allow for four PCI-E 16x and two PCI-E 8x lanes all at 3.0 speeds.

    For the majority of consumers, socket 1155 will remain good enough for 2012.

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