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Form Factors

How To Choose A Motherboard: A Guide For Beginners
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While large manufacturers are free to build PCs in whatever shape they desire, ATX and its derivatives dominate the do-it-yourself market. Smaller variations of ATX limit the room you have for expansion and make you more reliant on integrated or external devices, while allowing compact system dimensions. Even as advancements in on-board audio and network controllers have improved those subsystems to the point where you don't need add-in cards with those capabilities, on-die graphics are still fairly anemic. Unless you're only performing productivity tasks and watching video on your PC, you'll probably want a discrete card for 3D tasks. While office systems and media players may serve a fixed role throughout their useful lives, it's a good idea to have at least some room for expansion cards when building a multipurpose configuration.

ATX Through Mini-ITX

ATX was designed to address three major shortcomings of the earlier AT form factor, and it offers a few minor improvements as well. First, a designated portion of the board for the CPU socket keeps it out of the way of long cards, where AT boards had the CPU mounted behind or in place of card slots. Second, the inclusion of an I/O panel on the motherboard itself negates the need for slot brackets to break out common connections like USB, Ethernet, and audio. Third, a cooling path from the lower-front to the upper-rear of the case vents heated air through the power supply and/or an exhaust fan. All three major advancements are centered on splitting the board between the expansion and CPU areas.

Most significant of the more minor improvements was the addition of a power switch on the motherboard, rather than the power supply. This allowed the system to turn itself off at shutdown, and made possible features like wake-on-ring (using a modem), wake-on-LAN (using a network adapter), timed power up/power down, and keyboard power-on hot-buttons.

ATX derivatives are based on the same CPU section, so that smaller motherboards are able to fit into larger cases if desired. ATX standards include microATX and FlexATX. Most Shuttle-style PC cubes (often called SFF for Shuttle Form Factor or Small Form Factor) use a two-slot variation of the FlexATX form factor cut to approximately eight inches, and VIA further shortened its mini-ITX form factor to 6.75 inches by reducing the maximum slot count to one.

ATX size specifications are based on fractional inches, and rounding to the nearest millimeter is the most likely reason why the mounting holes of many motherboards are slightly misaligned with the mounting points of many cases. Even the originator of ATX, Intel, rounds the dimensions of recent specification updates when converting from original inch designations.

The image above compares the maximum size and maximum number of slots allowed on various ATX-based form factors, with dashed lines indicating how the mounting holes in smaller boards still align with those of larger cases. It also shows a long-forgotten solution to the problems of mini-ITX.

Before there were any high-performance products based on the mini-ITX form factor, AMD attempted to standardize Shuttle-style gaming cubes with a newer specification called DTX. Its single-slot derivative, mini-DTX, resembles mini-ITX except that it’s deeper, which makes room for four memory modules and a full-sized CPU voltage regulator. While most mini-ITX-optimized gaming cases are designed to hold a DTX motherboard, persistence of the mini-ITX moniker has prevented motherboard makers from taking advantage of the extra depth. As shown above, the same rule of “smaller motherboard fits larger case” applies.

Over The Top (Or Under The Bottom)

Oversized motherboards have existed for as long as any of the form factors mentioned above. One of the oldest is EATX, with its 13” depth (front to rear). Foxconn’s attempt to develop a 10-slot form factor succeeded only in introducing 10-slot cases to the market, and other manufacturers responded to the new cases by producing nine-slot-tall (13.6”) XL-ATX motherboards that can use the case’s tenth slot to hold a thick graphics card in the platform's bottom slot. The associated cases are specified as XL-ATX-compatible, and they'll still hold a full range of smaller boards down to mini-ITX.

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  • 1 Hide
    olafgarten , October 1, 2014 3:47 AM
    I'd be careful with the size, sometimes cases with large CPU cutouts can't support mini itx motherboards
  • 1 Hide
    kamhagh , October 1, 2014 4:33 AM
    i hate psu on top cases :S looks ridicules !!!
  • 2 Hide
    MeteorsRaining , October 1, 2014 4:35 AM
    Great article, it has info on every small aspect that most mainstream users neglect, and the comparision b/w the chipsets and PCIe lanes support is very useful for first timers.

    The fact that memory clearance and slots often get overlooked, its better to have 4 slots for the sake of upgradility. Higher profile sticks often obstruct in cooler installation too.

    The chipset part was comprehensive, too. Well ATX form factor is standard nowadays, and given that most mid towers support that, I'd get it over mATX anyday, for more space b/w the components like GPUs.

    Also, higher the speed, lower the CL, better the sticks, but the fact that APUs require faster memory for optimal performance, because they use it as VRAM, should be considered. Faster memory helps in OCing too, timings don't matter as much, but yes it should not fall beyond CL11 for 2400MHz.
  • -2 Hide
    Novuake , October 1, 2014 5:36 AM
    Damn, I was busy creating a tutorial on this exact subject! Sigh...
  • 2 Hide
    Onus , October 1, 2014 6:01 AM
    Thomas, I think you got a little lost (though I wouldn't quite say "mired") in motherboard description rather than motherboard selection. You went into great detail on what is available, but very little on why someone might want or need it.
    I too have thought about writing on this subject. Novuake, by all means continue with your effort. More data points are almost always helpful, and we know that newbs sometimes need all the help they can get.
  • 2 Hide
    Crashman , October 1, 2014 6:07 AM
    Quote:
    Thomas, I think you got a little lost (though I wouldn't quite say "mired") in motherboard description rather than motherboard selection. You went into great detail on what is available, but very little on why someone might want or need it.
    I too have thought about writing on this subject. Novuake, by all means continue with your effort. More data points are almost always helpful, and we know that newbs sometimes need all the help they can get.

    Pick a CPU based on the apps you already use (on the PC you didn't build) and plan to use
    Pick cards and storage
    Pick the size of the PC you want. Make sure it's big enough for your cards and storage
    Pick a motherboard that fits those parameters.

    The rest is just, well, mostly reassurance :) 
  • 0 Hide
    Onus , October 1, 2014 8:15 AM
    Quote:

    Pick a CPU based on the apps you already use (on the PC you didn't build) and plan to use
    Pick cards and storage
    Pick the size of the PC you want. Make sure it's big enough for your cards and storage
    Pick a motherboard that fits those parameters.

    The rest is just, well, mostly reassurance :) 

    This is one reasonable synopsis of the process. What is then necessary is a discussion of slots, ports, and desired options for tweaking, particularly relating to performance (e.g. native vs. 3rd party controllers, VRM quality and BIOS options for overclocking, etc), size constraints, with component quality/longevity thrown in as well.

    What is needed is a crosstab table of chipsets and the features they support; e.g. RAID versions, USB3.0, SATA 6Gb/s, etc.

  • 0 Hide
    lp231 , October 1, 2014 8:29 AM
    How to pick a motherboard
    1. Decided on whether you want to go with AMD or Intel
    2. Pick a board based on the CPU you want to have
    3. Look at socket type, socket type must match the CPU you're getting, so if your getting a socket 1150 CPU, the motherboard must also say socket 1150. Same with AMD, AM3+ CPU must have a board that says AM3+
    4. Large cases can fit large boards and small boards. But small cases cannot fit large boards. Best to check out the case specs to see what boards will fit.
    5. If you want to run 2 video cards, make sure the board has at least 2x PCIe x16 slots. Those that support CFX and SLI will most likely have the CFX or SLI logo on the motherboard box. But check the motherboard manual or do some online research to confirm on it.
    6. Rest are just feature you want to have or not like wifi, Bluetooth, or the need for surround sound speakers. Most audio ports will just be Red, Green, Blue Some board will have that as well as Orange, Black, and Grey.
    7. Most important, out of all of them is not to rush on it. Do some research and read lots of reviews before buying.
  • 2 Hide
    Amdlova , October 1, 2014 9:28 AM
    Can be better this tutorial.
  • 0 Hide
    ta152h , October 1, 2014 11:20 AM
    One nitpick, AM1 is the platform for Kabini, not the socket. The socket is FS1b.

    The AM1 socket was a different beast. I'm still not sure why AMD chose this name a second time, with that in mind.
  • 0 Hide
    catatech , October 1, 2014 11:21 AM
    Maybe a comparison of audio chipsets(alc1150, 892,...), network chipsets(Realtek, Intel...), wireless chipses(2x2, 2x3,...), USB supported modes(xfast,...), PS/2 support, ... will also be helpful. Since those components count when a someone buy a motherboard.
  • 0 Hide
    ta152h , October 1, 2014 11:55 AM
    One thing I'd add is to pay attention to the maker of the motherboard.

    I bought an ECS only because it was the only motherboard that had what I wanted. Yes, I know, I still should not have, but I didn't know just how bad they are. It wouldn't use top of the line memory, wouldn't keep memory timings I put in, constantly lost the time, and had a terribly loud fan, on a processor that topped out at 25 watts. Then it started putting up the wrong display resolution, and wouldn't let me change it to the appropriate values for my monitor. I'd have to reset the firmware, then it would work, then fail again two days later. Pure junk.

    Technical support was abysmal as well. They solved nothing, and just kept asking me to do things I had already done, and told them I had already done. Entirely useless. I basically just removed the motherboard once the AM1 platform came out, since it was similar enough (I had an a6-5200, on the KBN-I).

    I'll never get another ECS. Even if the motherboard was a lemon, the fact they couldn't assist at all, and had one firmware release a few weeks after the first, and then nothing after that, makes it clear the company isn't very good.

    I replaced it with an Asrock, because I wanted DisplayPort (this is another important characteristic of a motherboard, make sure it has the video output that matches your monitor, if you have an existing one you wish to use with it), and no more problems.

    So getting a reputable brand is always a good idea.
  • 1 Hide
    lp231 , October 1, 2014 11:57 AM
    Those that comes to toms will want to know a lot of details, and are willing to learn. But for a beginner that dont know what thg is, just tell them what they must match. like amd cpu with amd board. The rest like raid, chipset, pcie lanes and whatever else comes in later on. Giving too much info in the first place just confuses them even more or drives them away from building their own pc as they think its way too complex, so they go and buy prebuilts.
  • 0 Hide
    Crashman , October 1, 2014 12:13 PM
    Quote:
    Those that comes to toms will want to know a lot of details, and are willing to learn. But for a beginner that dont know what thg is, just tell them what they must match. like amd cpu with amd board. The rest like raid, chipset, pcie lanes and whatever else comes in later on. Giving too much info in the first place just confuses them even more or drives them away from building their own pc as they think its way too complex, so they go and buy prebuilts.
    This is our second overhaul since 2006. We plan to release future revisions in more-frequent, smaller steps. And I'd personally like ideas on how to make it easier to read. I might even be able to take some stuff out, but probably not much. More important is probably to make sure all of the information is organized in an easily-read manner. Also, there might be a couple not-too-technical things I could add.

    So, I'm open to suggestions.

  • 1 Hide
    zakaron , October 1, 2014 12:52 PM
    I remember my first motherboard swap back in '97, I didn't take into consideration the peripherals I owned to match the connector type. I bought a socket 7 board to run a Cyrix P133+ that had an AT connector for the keyboard... well the Pentium 60 board I was replacing had dual PS/2 ports. I already had a serial mouse, but I was out of luck on the keyboard. I had to go back the next day to the computer show at the ExpoMart to track down an AT to PS/2 converter. Lesson learned: always make sure you have the correct hookups for the peripherals you want to use. IE: do you need PS/2, IDE for that old DVD drive, serial (for legacy device), floppy controller if you still use those ancient things, enough USB ports or do you need a USB hub, etc.
  • 0 Hide
    Onus , October 1, 2014 12:55 PM
    I think some feature comparison charts or tables could be helpful. Put socket/chipset on the vertical, and feature along the horizontal. My original suggestion ties to the chipset only, and what catatech listed would differentiate motherboards with the same base chipset by listing other distinguishing features.
  • 0 Hide
    Crashman , October 1, 2014 1:07 PM
    Quote:
    I remember my first motherboard swap back in '97, I didn't take into consideration the peripherals I owned to match the connector type. I bought a socket 7 board to run a Cyrix P133+ that had an AT connector for the keyboard... well the Pentium 60 board I was replacing had dual PS/2 ports. I already had a serial mouse, but I was out of luck on the keyboard. I had to go back the next day to the computer show at the ExpoMart to track down an AT to PS/2 converter. Lesson learned: always make sure you have the correct hookups for the peripherals you want to use. IE: do you need PS/2, IDE for that old DVD drive, serial (for legacy device), floppy controller if you still use those ancient things, enough USB ports or do you need a USB hub, etc.
    Ouch. That stuff was in the previous versions of the beginner's guide. I was hoping that people would have settled down to SATA and USB by now, just to circumvent your issues, because they make the discussion a little boring and hard to follow.

  • 0 Hide
    kittle , October 1, 2014 1:22 PM
    Quote:
    This is our second overhaul since 2006. We plan to release future revisions in more-frequent, smaller steps. And I'd personally like ideas on how to make it easier to read. I might even be able to take some stuff out, but probably not much. More important is probably to make sure all of the information is organized in an easily-read manner. Also, there might be a couple not-too-technical things I could add.

    So, I'm open to suggestions.

    So... some suggestions

    Since this article is supposed to be for beginners:
    AMD vs Intel -- Need to pick one. why? Pros and cons for both
    CPU - Speed, # of cores, hyperthreading. whats good, whats not.. and why? (leave out any overclocking discussions)
    RAM - how much? .. what kind? and why?
    What chipset do I need/want. And why?

    -- note that each point has a "why" component. You seem to have left that out of your article.

    (Im leaving out PSU, HDD and GPU)


    As noted by @ta152h - the manufacturer of the motherboard matters a lot. Some companies make better boards on average that others. but as with everything there are compromises.. Better companies usually charge more.

    next a "how-to" section
    - how to make sure the CPU will even FIT the motherboard
    - how to make sure the CPU is compatible
    - how to pick the right RAM (focus on mainstream compatibility, not overclocking)
    - how to make sure the board will fit in my case (or how to pick a case for my motherboard)
    - how to pick a good motherboard manufacturer


    Lastly - since picking a motherboard usually means the person is building a new system, some basic recommendations would be helpful.
    Office/Kitchen system -- no gaming, or VERY light gaming
    - lower cost
    - high reliability (it wont be replaced anytime soon)
    - no overclocking
    - onboard graphics (or cheap gpu)
    - single HDD: 500gb/1TB HD,
    - 4GB ram
    - 300-400w PSU

    Gaming oriented system
    - mid to higher cost
    - dedicated GPU (single, no SLI)
    - overclocking available, but this is not a beginner subject
    - SSD boot drive & mechanical storage drive (2TB+)
    - 8GB ram or more
    - 650w PSU

    Anything beyond that.. and the person in question is not a beginner, so the article does not apply.
  • 0 Hide
    Crashman , October 1, 2014 1:41 PM
    Quote:
    Quote:
    This is our second overhaul since 2006. We plan to release future revisions in more-frequent, smaller steps. And I'd personally like ideas on how to make it easier to read. I might even be able to take some stuff out, but probably not much. More important is probably to make sure all of the information is organized in an easily-read manner. Also, there might be a couple not-too-technical things I could add.

    So, I'm open to suggestions.

    So... some suggestions

    Since this article is supposed to be for beginners:
    AMD vs Intel -- Need to pick one. why? Pros and cons for both
    CPU - Speed, # of cores, hyperthreading. whats good, whats not.. and why? (leave out any overclocking discussions)
    RAM - how much? .. what kind? and why?
    What chipset do I need/want. And why?

    -- note that each point has a "why" component. You seem to have left that out of your article.

    (Im leaving out PSU, HDD and GPU)


    As noted by @ta152h - the manufacturer of the motherboard matters a lot. Some companies make better boards on average that others. but as with everything there are compromises.. Better companies usually charge more.

    next a "how-to" section
    - how to make sure the CPU will even FIT the motherboard
    - how to make sure the CPU is compatible
    - how to pick the right RAM (focus on mainstream compatibility, not overclocking)
    - how to make sure the board will fit in my case (or how to pick a case for my motherboard)
    - how to pick a good motherboard manufacturer


    Lastly - since picking a motherboard usually means the person is building a new system, some basic recommendations would be helpful.
    Office/Kitchen system -- no gaming, or VERY light gaming
    - lower cost
    - high reliability (it wont be replaced anytime soon)
    - no overclocking
    - onboard graphics (or cheap gpu)
    - single HDD: 500gb/1TB HD,
    - 4GB ram
    - 300-400w PSU

    Gaming oriented system
    - mid to higher cost
    - dedicated GPU (single, no SLI)
    - overclocking available, but this is not a beginner subject
    - SSD boot drive & mechanical storage drive (2TB+)
    - 8GB ram or more
    - 650w PSU

    Anything beyond that.. and the person in question is not a beginner, so the article does not apply.


    I see what you're saying, but what I think you're really asking for are a CPU guide for beginners, a DRAM guide for beginners, a storage guide for beginners, and more "about you" stuff in the "how to build a computer" guide.

    That last thing, maybe an introductory article like "Beginner's Guide To Beginner's Guides: PC Tech 099"
  • 0 Hide
    Amdlova , October 1, 2014 1:51 PM
    No mention of power suppy. Crap sound. the only reason i get 130 us plus motherboards is because the sound some mother boards have snr 90 db.
    I don't care if the mother board will fly some high party lan or other things. I never used the ie 1394 plus E-sata...
    for now i got only asrock motherboards because sound nice with my edifier and my akg headphone.
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