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Both Bloomfiled and Lynnfield are examples of the Nehalam micro-architecture. Bloomfield is available at the time writing, and Lynnfield is expected probably in the second half of 2009. The Lynnfield architecture will include core i3, i5, and i7 parts. Some people are wondering if they should purchase a a Bloomfield now, or wait for Lynnfield. I have collected some information so that you can make comparisons. I am comparing the top Lynnfield (870) with the bottom Bloomfield (920), however the Lynnfield specification could change. Probably not for major architecture features, but processor speeds could change, etc.
The big differences are that Lynnfield drops the QPI peripheral bus, has one fewer memory channel, and a lower thermal dissipation. Some of the lower end Lynnfields disable hyper-threading, but the 870 does not.
QPI might be important if you are running an SLI setup, or some other PCIe-bus bandwidth intensive application. Lynnfield includes 16x PCIe on-die, so if you are running a single 16x PCIe GPU, you probably don't need to worry. Being on-die, it means that the CPU has a direct path to the GPU and doesn't need to go through an I/O controllers.
16x PCIe 2.0 == 8GB/s
QPI == 25.6GB/s
Aside from GPU, both Bloomfield and Lynnfield address other peripherals (USB/SATA/Network/Etc.) through a DMI bus. DMI == 10GB/s
The Lynnfield only has two memory controller. I understand this to mean that Lynnfield will support Dual-Channel, but not Triple-Channel configurations of DDR3 memory. Also, I haven't looked into it, but I expect that Lynnfield will run whatever fast ram. (DDR3 2133 or whater.) I don't see any reason for Intel to go backwards in this regard.
This article explores the effect of Dual versus Triple channel operation on a Core i7 920. http://www.techreport.com/articles.x/15967/1 . (When looking at the charts, compare the 1066 @ 9-9-9-27 results to the 1066 @ 9-9-9-27 (Dual) results). The increased bandwidth of Triple Channel does seem to have some positive effect in certain applications.
Finally, Lynnfield's lower TDP means that it runs cooler, and hopefully draws less power.
Anandtech speculates that Lynnfield's "secret sauce" will be in it's turbo-boost feature. Basically, if your application needs fast single-threaded operation, the CPU will dynamically lower the multiplier on some cores and up the multiplier on the core/thread that needs it. This sounds good for the everyday user. The OC'ers can correct me, but I suppose that they disable the turbo-boost functionality, and manually set the BCLK multiplier to its highest stable setting for all cores and leave it there.
In sum, it looks like Lynnfield Core i7 870 will be a budget alternative to the Bloomfield Core i7 920. The removal of QPI, and a memory channel should result in cheaper CPUs in time. Also, because the Lynnfield requires fewer support chips, motherboards should be cheaper. Presumably the 920 will yield better performance, but it will be at a cost. SLI users will probably avoid Lynnfield, in favor of Bloomfield's higher bandwidth graphics bus. This is ironic, because Lynnfield might shine in single threaded performance, which I believe affects gamers specifically.
If I got anything wrong up here, let me know, civilly. I put this together to help people, not to get flamed.
Sources:
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=3585
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=3570
http://en.wikipedia.org/wiki/Intel_Nehalem_(microarchitecture)
The big differences are that Lynnfield drops the QPI peripheral bus, has one fewer memory channel, and a lower thermal dissipation. Some of the lower end Lynnfields disable hyper-threading, but the 870 does not.
QPI might be important if you are running an SLI setup, or some other PCIe-bus bandwidth intensive application. Lynnfield includes 16x PCIe on-die, so if you are running a single 16x PCIe GPU, you probably don't need to worry. Being on-die, it means that the CPU has a direct path to the GPU and doesn't need to go through an I/O controllers.
16x PCIe 2.0 == 8GB/s
QPI == 25.6GB/s
Aside from GPU, both Bloomfield and Lynnfield address other peripherals (USB/SATA/Network/Etc.) through a DMI bus. DMI == 10GB/s
The Lynnfield only has two memory controller. I understand this to mean that Lynnfield will support Dual-Channel, but not Triple-Channel configurations of DDR3 memory. Also, I haven't looked into it, but I expect that Lynnfield will run whatever fast ram. (DDR3 2133 or whater.) I don't see any reason for Intel to go backwards in this regard.
This article explores the effect of Dual versus Triple channel operation on a Core i7 920. http://www.techreport.com/articles.x/15967/1 . (When looking at the charts, compare the 1066 @ 9-9-9-27 results to the 1066 @ 9-9-9-27 (Dual) results). The increased bandwidth of Triple Channel does seem to have some positive effect in certain applications.
Finally, Lynnfield's lower TDP means that it runs cooler, and hopefully draws less power.
Anandtech speculates that Lynnfield's "secret sauce" will be in it's turbo-boost feature. Basically, if your application needs fast single-threaded operation, the CPU will dynamically lower the multiplier on some cores and up the multiplier on the core/thread that needs it. This sounds good for the everyday user. The OC'ers can correct me, but I suppose that they disable the turbo-boost functionality, and manually set the BCLK multiplier to its highest stable setting for all cores and leave it there.
In sum, it looks like Lynnfield Core i7 870 will be a budget alternative to the Bloomfield Core i7 920. The removal of QPI, and a memory channel should result in cheaper CPUs in time. Also, because the Lynnfield requires fewer support chips, motherboards should be cheaper. Presumably the 920 will yield better performance, but it will be at a cost. SLI users will probably avoid Lynnfield, in favor of Bloomfield's higher bandwidth graphics bus. This is ironic, because Lynnfield might shine in single threaded performance, which I believe affects gamers specifically.
If I got anything wrong up here, let me know, civilly. I put this together to help people, not to get flamed.
Sources:
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=3585
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=3570
http://en.wikipedia.org/wiki/Intel_Nehalem_(microarchitecture)