[clue-tech] case type

[Roy J. Tellason]

On Saturday 11 April 2009 06:40:20 pm Soleblaze wrote:
> Collins Richey wrote:
> > Here's a stupid question. How does one tell the form factor of a
> > computer case (atx, or ...)? I have an old but still usable case with
> > a dead motherboard, so how do I know what kind of replacement board
> > would fit?
>
>  From what I remember the biggest difference between AT and ATX was that
> AT power supplies had an actual button that would attach to the front of
> the case, while ATX would use a wire that goes from the motherboard to
> the button.
>
> I'd probably measure the board and look it up.  If it looks like a
> regular sized case, it's probably ATX.  Wikipedia is also your friend:
> http://en.wikipedia.org/wiki/Comparison_of_computer_form_factors

Oh heck,  I didn't think we were talking about AT vs. ATX,  I thought we were 
talking about ATX vs. ITX and some of the other newer variants.  I didn't 
think that anybody besides myself was still using AT-cased stuff.  :-)  (BTW,  
if anybody needs some older stuff feel free to contact me offlist,  I have 
bunches of it.)

AT cases have the same PS connector that goes all the way back to the original 
PC,  or I should probably say connectors,  since they were usually a pair of 
them,  though I can't see any reason why they couldn't be a single connector.  
The key point there is to keep the black (ground) wires together in the 
middle where they meet.  They also typically have the older-style 5-pin 
(larger) DIN connector for keyboard,  and mostly don't provide a mouse 
connector -- that's handled separately,  and some of what I have on hand here 
uses a slot bracket with a short cable going to a pin header,  though I think 
I have one that does have a pair of mini-DIN connectors...

ATX boards use a single molex connector with 20 or 24 pins (and sometimes an 
extra one for MB power besides),  a bunch of I/O that's all on the MB,  
typically a metal shield plate that stays with the MB as someone else 
mentioned,  and something of a different form factor than AT boards do.  They 
also typically expect 3.3V power (which AT boards don't) and a +5V "standby" 
power that's on all the time that the machine has power,  which is used for 
the wakeup stuff,  whether it's the power switch,  wake-on-LAN,  wake-on-ring 
(modem),  etc. functions,  which are present to varying degrees and enabled 
or not in the BIOS via the setup stuff in CMOS.  Typically the keyboard and 
mouse connectors are 6-pin mini-DIN that are stacked vertically.  There are 
probably a number of other differences that I'm not thinking of at the moment 
besides.

Then there are variants of ATX,  like ITX,  and I can't recall what else,  
that are more a matter of size than anything else.


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