[conspire] How to check if a mobo is compatible with Linux

Rick Moen rick at linuxmafia.com
Sun Mar 23 10:24:36 PDT 2008

Quoting K Sandoval (indigo.kai at gmail.com):

> Kai: well...  Thinking, I guess I really don't "need" a floppy drive
> :::looking at a box FULL of old floppies with old versions of DOS and
> windows 3.1::::  Hey that's right I am a LINUX person NOW!!!  I can
> learn to mount & boot from a thumb drive if necessary...  Floppies?!?
> Floppies!?!  We don't need any stinken Floppies!!!

Well, they had their day -- especially in the 1980s, when floppy media
quality didn't utterly suck, and you had some chance that those small,
unbelievably slow storage devices would reliably hold data for the next
decade.  But 1.44MB storage devices, in an era when people are giving
away relatively lightning-fast, nearly indestructable 64MB USB flash
drives like candy, seem rather quaint.  These days, people use CDR or
DVD-ROM media for archival storage, and either USB flash drives or
ethernet / wireless networking for casual data transfer.

> I already have 3 IDE/PATA drives.

Ah.  I was previously unclear on that.  _Buying_ a PATA drive for a
newly built machine that would use a new motherboard supporting either
PATA or SATA (or both) was the part that sounded questionable.

> Two of these drives I use with a removable hard drive bay currently in
> my eMachine.  And then one new/unused 350GB IDE Drive.  I had
> originally thought of using the 350 GB drive with the eMachine as a
> slave drive.  However I am not sure if the eMachine has the ability to
> see/handle such a large drive.

I would imagine so.

ATA ("IDE") has indeed been saddled with a series of rather pathetic
size barriers over the years, which have all had to be kludged past
through extensions to the motherboard BIOS's addressing schemes.  The
technical write-ups on this will make your eyes cross -- and we SCSI
bigots just shake our heads and wonder how people manage to design
things so badly in the beginning that they have to keep incrementally 
repairing the standard, over and over.  Here's one of the better
(and less mind-numbing) write-ups:


Note the bit about how the latest ATA kludge was the "ATA-6" one that
extended the count of drive sectors to a 28-bit or 48-bit scheme,
permitting addressing ATA devices with up to 137 gigabytes or 144
petabytes[1] of storage, respectively.  The latter scheme is most often
called "48-bit LBA" (linear block addressing).  

In an ideal world, you'd be able to check in the BIOS or motherboard
documentation and find out that the BIOS either does or do not do 48-bit
LBA.  However, if you want to answer that question for your eMachine,
and you already have the 350GB drive in hand, it's probably easier to
just plug it in and find out -- as you say.

> I supposed I could price SATA HD and consider a new drive for the new system.

{shrug}  If you want.  It's your money.  I hadn't known you already had
a hard drive for the system, y'see.

> The idea of getting/purchasing an "external" CD/DVD Burner is
> something I had not considered before but I can understand the
> reasoning.  I do plan to get an ATX  case with lots of airflow, 2
> fans, and I already have some of the "round" IDE cables.


OK, before I talk about the "round" IDE cables, let's talk about heat,
airflow, cases, and PSUs (power supply units).  You're ahead of the game
in proposing to _get_ a case.  Most people just use whatever really
crummy no-name cases they already have -- and then do things like cram
them with heat-producing gamer video cards and 10kRPM hard drives.  Some
of those cases are really tiny, and yet have really bad heat
dissipation.  Why?  Because customers have no idea what they _should_ be
looking for, don't value quality, and don't insist on avoiding junk --
so junk predominates, and non-junk becomes a slightly exotic specialty
item.  See:   http://linuxmafia.com/~rick/lexicon.html#moenslaw-bicycles

Not all fans are created equal.  A reliable, useful, and quiet fan is
one with good bearings, for starters, and commodity fans have cheap
"sleeve" bearings that are noisy and prone to seizing up without
warning.  If there's room, it's better to have larger-diametre fans
instead of tiny ones, as the wider ones can move more air without having
to spin at extremely high rates of rotation, which increases noise and
bearing wear.

For example, I have an old mid-tower VA Linux Systems StartxMP workstation
box (ATX, PII motherboard) which always struck me as being annoyingly
loud, so one day I was at Central Computer and bought two replacement
case fans of the same size -- a good brand with decent bearings:  Cooler
Master, or Antec, or something like that.  It made a night-and-day
difference in the noise levels, and also I'm sure made it far less
likely that the case will suffer seize-up of the fans, which of course
can contribute to a runaway heat buildup scenario.

It's always in your interest to use quality PSUs.  By "quality", I'm not
just referring to the alleged maximum wattage figure, because those are
often fibs, i.e., cheap PSUs often cannot really deliver that wattage
reliably, with consequent severe risk to the attached motherboards, RAM,
and (especially) hard drives.  (Overstressed or malfunctioning PSUs kill
almost as many computer compoents as does runaway heat buildup.)

My standard advice about PSUs:

I have a strong prejudice towards several brands of rather bulletproof,
conservatively designed PSUs:  Cooler Master, Enermax, PC Power &
Cooling, or in a pinch Sparkle aka SPI.  None other.  People tell me
occasionally that some others such as Seasonic are also good, and they
may be right.

Back to the "round" cables.  PATA was designed to use a ribbon cable:  
The bus design alternates signal and ground lines (40 or 80 total),
which intentionally are physically adjacent.  See:

PATA's alternation of signal and ground wires, at a fixed separation
between them, keeps the impedence of the bus approximately correct, and
prevents crosstalk between conductors on account of capacitive coupling.  
This is very important to reliability of the connection.

"Round" PATA cables, where the connectors are gathered into a
round-cross-section bundle, thus completely and thoroughly violate --
trash -- the ATA cable specification.  If you're lucky, you get away
with that violation, but it's a really awful idea, really.  Yes, you do
get slightly better airflow, but it's still a bad idea:  You could, in a
worst-case scenario, suffer silent progressive corruption of all data
passing along the PATA bus.  Or, you might get mysterious failures of
other sorts.  Or, you might get away with it.

Why do botched solutions like "round" PATA cables do so well in the
marketplace, with the result that people pay good money to shoot
themselves in the feet?  For the same reason why the 1970s saw a
nosedive in the quality of available bicycles:

> I do agree that in regards to RAM it seems like the best bet is to
> simply invest in the RAM now, and purchase two 2GB sticks with
> "sufficient density" now verses upgrading later.

OK, but, just to be clear, "density" in this context merely means "the
amount of RAM one gets per stick".  So 2GB/stick _is_ the density in
this context.  

The idea is that, if you have only two RAM slots on a motherboard, then,
say, buying a pair of 512MB sticks today is probably a bad idea, if your
aim is to eventually have 4GB total on the system.  Why?  Because any
RAM upgrade whatsoever is going to require that you remove at least one
of the existing 512MB sticks and put it in a drawer.  

If, instead, you started out with a single 2GB stick (instead of two
512GB ones), then you can later flesh out the system by adding a second
2GB stick without having to waste any existing RAM.

Naturally, you _hope_ that RAM you "stick in a drawer" won't get wasted,
because you'll find a second computer system to migrate it to.  However,
over time, people's drawers get an accumulation of low-density RAM that 
has nowhere it can be reasonably deployed.  There it stays, until one
day, you look at it and realise it's too obsolete to keep, and then it
becomes landfill.

Which brings up another subject:  By no means is all RAM
interchangeable.  Sorry.  ;->

[1] An almost unfathomably large figure:  kilo, mega, giga, tera, peta.

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