Choosing a motherboard

[not_here.5.species8350]

When people build their own pc's how do they determine which motherboard will fit their case?

 

[Paul]

When people build their own pc's how do they determine which motherboard will fit their case?

Motherboards belong to form factors.

ATX come in regular and microATX. The regular ones are 12"x9.6".
The microATX are 9.6"x9.6".

The holes are drilled in standard places. There might be nine
standard drill holes for example. At least, I remember nine
holes on my old Nforce2 motherboard.

If the motherboard is narrower than standard, such as en
el-cheapo 12"x7.0" motherboard, then the right hand edge of
the motherboard is poorly supported. (Only six of the nine possible
screws and standoffs can be used.) A home builder might put an
insulating object under that edge, if they suspected
they could damage the board while pressing on it. So while
an ultra cheap full sized ATX might save money, it has the
potential exposure that the right hand edge "flaps in the breeze".
The smaller motherboard size, saves the factory a few pennies on
board costs. The vertical dimension is still standard. A home
builder checks the adverts, before buying, to see if the board
is big enough, to have all nine holes in it.

*******

After Intel did ATX, they did a followup called BTX. More pre-built
systems used that, than home builders. I have nothing but home-built
ATX systems here, no BTX. The BTX form factor is "upside-down" and
the layout of components is entirely different. The add-in card
slots of BTX, won't align with the holes in an ATX computer case.

A few computer cases were made, which support both ATX and BTX,
and the case must be slightly disassembled, to convert from one
mode to the other.

The BTX will have mounting holes in standard locations. The
standards, such as they are, exist, so that computer case
manufacturers can make things that will actually work with
the motherboards.

Intel keeps a site, called formfactors.org , with documentation,
but the site is hard to search. I know of the existence of
certain documents, but need to use an external search engine
to actually find them. So while that site is a document
repository, it was designed by idiots. It doesn't perform
the intended function.

This will likely give you a better overview, than the formfactors.org
site. Note that BTX have different external dimensions, than ATX.

http://en.wikipedia.org/wiki/Computer_form_factor

When building a computer, you match them by names. You use
a mini-ITX motheboard with a mini-ITX case. And so on. And
in the case of "cheap bastards", you verify what the impact
will be, if material was shaved off one edge of the design
(the 12"x7" el-cheapo idea).

Paul

 

[Flasherly]

On Tue, 23 Apr 2013 04:07:48 -0700 (PDT),

When people build their own pc's how do they determine which motherboard will fit their case?

I don't. Not beyond "the standard" atx or mini-atx, which most
homegrown PC sizes are. I look at the standoffs beneath holding the
MB up and use whatever I have. If missing/mismatched one or two
standoffs, no big deal. Sometimes I put the MB on a towel and
assemble it first before sticking it in -- memory & CPU/fan. If
there's not a standoff near where something needs to be plugged/pushed
in - the main PS plugs or a video card, be careful not too adversely
to flex the MB or risk damage. (Stick a piece of Styrofoam or rubber
block beneath for a fair to close fit for support, in the rare
instance there's a flex point near a missing standoff. Better/best is
to make one's own standoff from a generic white neoprene one -- mounts
to MB and not the case for makeshift support.)

Match the case backplane tin I/O plate (keyboard/usb/audio block)
included w/ a MB, or forget it if you don't (it'll just get dustier
sooner). Those "strips" are also a part of the "case backplane" for
PCI/PCI-E add-on cards, like video.

Everything about a build should be modular once unscrewed. Screws
always first and best. Mylar bands are OK if in need and judiciously
applied. (I may use garbage bag ties indiscriminately.) And be extra
careful when seating a CPU's cooling that it's done right - assembled
and ready for a good layering of heatsink compound, as thin as
possible to be functionally adequate.

Some fudging on it is OK as long as you remember a computer is a
delicate instrument. Safer is don't if not certain if fudging the
wrong thing the wrong way may be, how to say, an indelicate
proposition at best.

A brite Cree LED flashlight. Magnet on wand to get screws or
pre-magnetize the the screw heads to a screwdriver tip. Long thin
pliars for jumper blocks. Magnifier and nose unafraid of getting a
dust spot on its tip.

 

[not_here.5.species8350]

I don't. Not beyond "the standard" atx or mini-atx, which most

homegrown PC sizes are. I look at the standoffs beneath holding the

MB up and use whatever I have. If missing/mismatched one or two

standoffs, no big deal. Sometimes I put the MB on a towel and

assemble it first before sticking it in -- memory & CPU/fan. If

there's not a standoff near where something needs to be plugged/pushed

in - the main PS plugs or a video card, be careful not too adversely

to flex the MB or risk damage. (Stick a piece of Styrofoam or rubber

block beneath for a fair to close fit for support, in the rare

instance there's a flex point near a missing standoff. Better/best is

to make one's own standoff from a generic white neoprene one -- mounts

to MB and not the case for makeshift support.)



Match the case backplane tin I/O plate (keyboard/usb/audio block)

included w/ a MB, or forget it if you don't (it'll just get dustier

sooner). Those "strips" are also a part of the "case backplane" for

PCI/PCI-E add-on cards, like video.



Everything about a build should be modular once unscrewed. Screws

always first and best. Mylar bands are OK if in need and judiciously

applied. (I may use garbage bag ties indiscriminately.) And be extra

careful when seating a CPU's cooling that it's done right - assembled

and ready for a good layering of heatsink compound, as thin as

possible to be functionally adequate.



Some fudging on it is OK as long as you remember a computer is a

delicate instrument. Safer is don't if not certain if fudging the

wrong thing the wrong way may be, how to say, an indelicate

proposition at best.



A brite Cree LED flashlight. Magnet on wand to get screws or

pre-magnetize the the screw heads to a screwdriver tip. Long thin

pliars for jumper blocks. Magnifier and nose unafraid of getting a

dust spot on its tip.

Thanks for the response.

I was particularly interested in your comments regarding the backplane.

'Match the case backplane tin I/O plate (keyboard/usb/audio block)
included w/ a MB, or forget it if you don't (it'll just get dustier
sooner). Those "strips" are also a part of the "case backplane" for
PCI/PCI-E add-on cards, like video.'

It looks like the Dell Dimension E520 case has a backplane that is part of the case. This makes choosing a motherboard difficult since the holes and slots must align for input/output sockets and cards.

Best wishes.

 

[Paul]

Thanks for the response.

I was particularly interested in your comments regarding the backplane.

'Match the case backplane tin I/O plate (keyboard/usb/audio block)
included w/ a MB, or forget it if you don't (it'll just get dustier
sooner). Those "strips" are also a part of the "case backplane" for
PCI/PCI-E add-on cards, like video.'

It looks like the Dell Dimension E520 case has a backplane that is part of the case. This makes choosing a motherboard difficult since the holes and slots must align for input/output sockets and cards.

Best wishes.

Did you check to see if the I/O shield metal pops out ?

On retail motherboards, every motherboard comes with a shield.
You pop out the old shield, and fit the new shield. Then install
the new motherboard. The I/O connectors on the motherboard, fit
through holes in the shield. And metal tabs on the shield, press
against the metal of each "stack". Doing so, provides minimal
improvement in EMI, and also may make a slightly better path
for static discharges (into the chassis).

If you're replacing "like with like" motherboard, then there
is no need to worry about the shield, as the holes should be
in the correct places. The same shield could be reused.

Paul

 

[Flasherly]

Dell uses the same generic MBs I buy. I know because I've bought
unnamed/rebadged MBs produced for Dell. Some Dells do fit a generic
standard for cases. Use your experience with the Dell for next time
and buy/build generic if possible. Makes things a whole lot easier.
Well, would be if there were I way I could dump years of experience
building computers on you. Modularity and standards, and enough
people doing it to make it worth your while.