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Choosing The Right Processor Socket

Best Of Tom’s Hardware: Beginner’s Guide To Motherboard Selection
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While many builders prefer the latest CPU technology, two older CPU sockets have remained on the market as manufacturers produced less-expensive CPU models to support even the lowest budgets. The oldest of these, Intel’s LGA 775, is being phased out, while AMD’s Socket AM2, which is newer, is expected to follow. AMD’s Socket AM2+ and AM3 and Intel’s LGA 1366 and 1156 are well-established replacements for the former CPU interfaces. We arranged brief descriptions in reverse chronological order.

Intel LGA 1156

Supporting Intel’s Core i3-, i5-, and 800-series i7 microprocessors, LGA 1156 motherboards connect two channels of DDR3 memory and 16 full-speed (5.0 Gb/s) PCIe 2.0 lanes directly to the processor. Because all northbridge functions, including memory and primary PCIe control, have been moved onto the processor, additional PCIe connections are available only through the "southbridge" component that remains on the motherboard itself, a part Intel has renamed as its Platform Controller Hub (PCH). Using the slower DMI interface (traditional for Intel northbridge-to-southbridge connections), the PCH provides only 2.5 Gb/s per pathway, and is therefore unsuitable for high-bandwidth applications such as graphics cards.

Because of its PCIe limitations, LGA 1156 is generally best-suited for users who require very few high-bandwidth expansion cards, including some users who rely almost exclusively on CPU performance. An acceptable workaround for the PCIe limitation has also been found for certain motherboard and high-performance graphics configurations.

AMD Socket AM3

Socket AM3 motherboards are nearly identical to similarly-named AM2+ models, but have DDR3 memory slots. Because Socket AM3 processors support both DDR2 and DDR3, AM3 processor users can choose between AM3 and AM2+ motherboards depending on memory preference. Current prices for DDR2 and DDR3 4GB dual-channel kits are similar, but we expect DDR3 will eventually be the better value as production of DDR2 declines.

Intel LGA 1366

Supporting 900-series Core i7 processors, LGA 1366 provides the motherboard with three memory channels and a high-bandwidth QPI interface for its chipset. Originally home to several quad-core processors, most early LGA 1366 motherboards will also support six-core models via a BIOS update. Yet, the most common reason buyers choose LGA 1366 isn’t for the processors it supports, but for the high number of PCIe lanes supported by its accompanying X58 Express chipset. Thus, LGA 1366 is the best choice for users who need both top CPU performance and added support for high-bandwidth expansion cards.

AMD Socket AM2+

AM2+ motherboards bridge the gap between the company’s DDR2 and DDR3 products by supporting Socket AM3, AM2+, and AM2 processors. To enable cross-compatibility, AM2+ motherboards support the higher-speed HyperTransport 3.0 interconnect of AM2+ and AM3 processors as well as the slower HyperTransport interconnect of Socket AM2 processors. Because Socket AM2 and AM2+ processors support DDR2 exclusively, all AM2+ motherboards have DDR2 sockets.

Because of its flexibility, Socket AM2+ is the best solution for anyone who wants to build an AMD-based personal computer using DDR2 memory.


AMD Socket AM2

AMD’s Socket AM2 processors are compatible with newer AM2+ motherboards, which in turn are also compatible with AM2+ and AM3 processors. Because of this, anyone concerned about upgrade or service replacement capability should skip this generation of motherboards entirely, even if they’ve chosen an AM2 processor.

Intel LGA 775

Intel's first “pinless socket” for desktop processors, its LGA 775 originally addressed the issue of high-speed Pentium 4 processors drawing too much power by increasing the number of connections. Intel credits the design for eliminating the lead-based solder formerly used for attaching socket pins. Unfortunately, flexible contacts within the socket can be very fragile and repeated rebuilds have left many testers with dead boards.


Currently being phased out in favor of its later LGA 1156 interface, the use of low-cost processors is the only reason to choose LGA 775 over its replacement. New LGA 775 motherboard models have supported Core 2-series processors since 2006, although newer processor models often require a revised motherboard BIOS just to get the system to boot. Most new purchases are not affected by these compatibility issues, but buyers should check the motherboard manufacturer’s CPU support list if the question of compatibility arises.

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Top Comments
  • 15 Hide
    quantumrand , February 11, 2010 5:31 AM
    Top choices for motherboards right now: Gigabyte, Asus, and MSI. Gigabyte is really the way to go, but there are a few Asus and MSI configs that you might prefer.
  • 14 Hide
    Crashman , February 11, 2010 7:01 AM
    one-shotWhat about EVGA?


    I'll let you in on a little secret: EVGA motherboards are a pain to overclock. Since that's EVGA's market, it's kind of a big deal. As an inexperienced manufacturer they're learning quickly, so hopefully we'll see the kinks worked out pretty soon.
Other Comments
  • -4 Hide
    shiroikaze , February 11, 2010 5:19 AM
    Seeing how I just built my first computer a couple days ago, this article came a little too late for me :p 

    Could've made my purchasing alot more quicker and painless.
  • 2 Hide
    micky_lund , February 11, 2010 5:30 AM
    ahh...the p55a-ud4p..great board
  • 15 Hide
    quantumrand , February 11, 2010 5:31 AM
    Top choices for motherboards right now: Gigabyte, Asus, and MSI. Gigabyte is really the way to go, but there are a few Asus and MSI configs that you might prefer.
  • 1 Hide
    one-shot , February 11, 2010 6:08 AM
    quantumrandTop choices for motherboards right now: Gigabyte, Asus, and MSI. Gigabyte is really the way to go, but there are a few Asus and MSI configs that you might prefer.


    What about EVGA?
  • 0 Hide
    tacoslave , February 11, 2010 6:11 AM
    quantumrandTop choices for motherboards right now: Gigabyte, Asus, and MSI. Gigabyte is really the way to go, but there are a few Asus and MSI configs that you might prefer.


    ah yes i got a got a msi 790fx gd70 with a combo from newegg (phenom II 955)and i absolutly love it. The best part is the overclocking utilities
    you can overclock fuckin everything in 5 min or less. Then i got another motherboard from zotac for 60 bucks (before rebate) and it died on me in less than a month and i'm still waiting on a rebate.
  • 14 Hide
    Crashman , February 11, 2010 7:01 AM
    one-shotWhat about EVGA?


    I'll let you in on a little secret: EVGA motherboards are a pain to overclock. Since that's EVGA's market, it's kind of a big deal. As an inexperienced manufacturer they're learning quickly, so hopefully we'll see the kinks worked out pretty soon.
  • 7 Hide
    porksmuggler , February 11, 2010 7:15 AM
    Great article for beginners. A quick browse through newegg, and I've built with every brand except EVGA, ZOTAC, and XFX (EVGA and XFX for graphics cards though). I've consistently gone with ASUS for my own and Gigabyte for customers when at all possible. I prefer ASUS for the best overall quality and Gigabyte usually provides the best value. I'm seeing a lot of comments for MSI lately, though I've never put them in the same league.
  • 2 Hide
    skora , February 11, 2010 7:32 AM
    This is a great reference article Crash. Lots of great info about chipsets, but I think the spot for socket type should be made long before choosing a mobo when spec'ing a rig. Is this part of Pauls "Balanced" articles?
  • 1 Hide
    Crashman , February 11, 2010 7:34 AM
    skoraThis is a great reference article Crash. Lots of great info about chipsets, but I think the spot for socket type should be made long before choosing a mobo when spec'ing a rig. Is this part of Pauls "Balanced" articles?


    http://www.tomshardware.com/reviews/beginners-guide-motherboard-selection,1289.html
  • 4 Hide
    nzprogamer , February 11, 2010 7:53 AM
    it takes long time to read all the information here but its all good to know for 1st time builder, love it. will there be some other advice like how to keep the case cool ( how to point the fans and where )?
  • 0 Hide
    skora , February 11, 2010 8:19 AM
    Quote:
    http://www.tomshardware.com/reviews/beginners-guide-motherboard-selection,1289.html

    I'd say you're article came first. Nice update!!!
  • 4 Hide
    Crashman , February 11, 2010 10:11 AM
    nzprogamerit takes long time to read all the information here but its all good to know for 1st time builder, love it. will there be some other advice like how to keep the case cool ( how to point the fans and where )?


    Eventually there will be an update to this article:

    http://www.tomshardware.com/reviews/build-part-1,1364.html
  • 0 Hide
    saran008 , February 11, 2010 10:21 AM
    Great guide for Beginners!
    Tom always rocks!
  • 0 Hide
    ytoledano , February 11, 2010 11:00 AM
    Given that the motherboard is one the least reliable components in any computer, the most important factor, IMO, is reliability.
  • 0 Hide
    saint19 , February 11, 2010 11:55 AM
    Very good article, currently I have a MSI K9A2 Platinum and works very good with my X4 955. I'm waiting for Fermi to change my mobo and RAM, and I would get an ASUS or Gigabyte...or maybe the 790FX-GD70.

    EVGA build excellent mobos, the problem is that only are for Intel processors and are very expensive ($499.99), with that price you can get the half of a good rig.
  • 0 Hide
    Anonymous , February 11, 2010 12:26 PM
    I had that Gigabyte X48T-DQ6... twice. Both had some kind of error that screwed up my internet connection, so I finally switched to an ASUS P5Q Deluxe. No more problems since.
  • 0 Hide
    Onus , February 11, 2010 12:46 PM
    I've had excellent results from ASRock, who seem to offer pretty high bang/buck. Even Foxconn is using more solid caps now, and doing so is probably what has allowed MSI to improve its quality image.
  • 0 Hide
    KupuAnd1 , February 11, 2010 12:52 PM
    I ones got a MSI board (like 5 years ago) and it was superb for reliability never dies and then I sold it. Now I got an EVGA and it is good.

    Waiting for USB 3.0 to go mainstream in boards to upgrade my mobo. I think right now is the best choice for future proof.
  • 0 Hide
    nevertell , February 11, 2010 1:09 PM
    Hey, that's my asus mobo. Although mine is underused, the other pci-e slot is empty because of the lack of money :( .
  • 1 Hide
    huron , February 11, 2010 1:22 PM
    Very nice article. It does include considerations when making a purchase and includes many details about components and all sorts of choices. Already forwarded it to a few people for reading - mostly people who want to know more, but no idea where to start.

    I hope you keep up this series - detailed articles to help beginners make decisions. This could be the starting point for many people

    Thanks again.
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