- Remember that the POST stands for
power on self test.
And it's something that your BIOS does
when your computer starts up.
But what if you can't see anything on the screen?
Well, if you can't
you're gonna want to use some type of POST tester
and we're gonna show how to use a POST card tester,
but you don't see these that often anymore
for PCI express.
However, some motherboards include a POST tester
and will show that on the motherboard
within the AV editor computer.
So let's get started.
- [Narrator] Let's talk about POST devices.
The POST is the power on self test
and we know that the motherboard does this
the BIOS,
or your UEFI does this.
And it checks all your devices.
Now what's great about the POST is
if there's a problem
you might get a beep code.
You might see an indicator light in here.
You might get a message on the screen.
But what if you don't get any of those things?
And you're not sure what the problem is.
Well, then you can use a POST device,
a POST tester,
to find out what the problem is,
which is quite often
one of the big four that we talked about,
CPU, RAM, motherboard,
or video card.
And there's various types of POST devices.
Back in the day you'd use a card,
and the card would be a PCI card.
And you'd connect the card,
then boot up the system
and there would be a readout
with the two digit display,
and you'd find out what the code means
within a book or online documentation,
or what have you.
Nowadays you don't have PCI slots as much anymore,
and you're gonna be hard pressed
to find a PCI express POST card.
You might find one,
you might find a USB tester.
But I gotta be honest with you,
they're generally not necessary.
I've used the POST testers in the past.
Maybe once out of every 50 computers
that I worked on.
And with the newer UEFI
it's not as necessary to be honest with you.
But the best types of POST device is the one
that's built into the motherboard.
And that's one of the reasons I chose this motherboard
cuz it has a built in POST tester
and the two digit code is right here.
So when you boot the computer,
it'll run through a series of codes
and it'll stop if there's an error.
So everything is connected now.
I connected everything back up
from the previous lessons.
And so we're gonna boot the system now.
And you can see the various codes
it's going through.
It's testing everything.
And generally with these POST testers
if it ends at 00,
or FF,
you're in good shape.
And that means that the system has booted properly.
And for this device, AA is also okay.
That's a special code
and that's actually all right.
Now, if you wanna learn more about the codes
for your POST tester,
you wanna look at the documentation.
And so that might come with a book.
If it's an external POST tester,
or if it's say an external USB,
or an internal PCI POST tester,
and it might come in the book,
the manufacturers documentation with the motherboard.
And this motherboard is from Asus.
And these are known as Q codes.
That's what they call 'em.
So there's a whole ton of them
a whole different list of problems that could occur,
but the AA is okay
and the system will boot all right
if it's set on AA.
Now there's a lot of other possibilities obviously.
You saw there's probably dozens there.
So I'm gonna shut down the computer
and pull a stick of RAM,
and then reboot
and see what error message we get.
Okay. So always make sure that
the little lead light on the motherboard
has turned off before you touch anything inside the system.
And so I have removed all of the RAM sticks.
And so now we'll power the computer back up.
Okay. And it goes through a couple codes,
and right away it stops at the 53 code.
Now this is hexadecimal by the way.
So you can have a lot of different options here.
You might see numbers or letters.
And if we were to look at
our manufacturers documentation here,
we'd see down here,
50 through 53,
is a memory initialization error.
Invalid memory,
incompatible memory,
or in this case, no memory
that's what we have in this case.
So you can look up what's happening
and these codes are usually right.
If you have an issue
with incompatible memory,
or if you have, you know,
two sticks that are not the same,
two different speeds,
or they're in the wrong slots, you know,
you'll usually get a 50 through 53 code.
So I'm gonna fix that right now.
We'll shut down the system
and it hasn't even booted properly
because there is no memory in there.
Wait for that lead to go out
and I'll put the RAM back in and boot it back up.
Okay. So I put the RAM back in
and always be sure to use your documentation.
You wanna know where your RAM is supposed to go.
If you're using dual channel,
or tri channel,
or quad channel, you know,
there's gonna be a whole diagram
and then description of what the slots are.
So make sure you're putting them in the correct location.
And so we'll boot this guy back up.
Let that guy run through.
And again, usually this is a problem with connections
or a device isn't there,
it's missing or it's incompatible.
And usually you can find these things with your eyes.
You can find out what the problem is generally.
But here we go.
AA is the code.
Everything's good.
That's how this normally boots and we're in good shape.
So now we can use the system to our heart's delight.
So that's POST testing
and this is outside of what the BIOS
or UEFI does for you.
This is beyond that.
So it's diagnostics
in the case that
you can't see anything on the screen,
and you don't hear anything on the computer.
And again, older devices, you could use a PCI version.
Again. I rarely use that.
Maybe one out of every 50 computers.
And you might see a PCI express,
or a mini card version,
or a USB version,
but the best ones are the ones that built
into the motherboard
but they all work essentially the same.
It's a two digit code
and you have to cross reference that
to your documentation,
to find out what the error is.
But keep in mind
if you see something like AA, or 00, or FF,
generally, that means the system's booting properly.
And you wanna look elsewhere for the problem.
And so that's it for this sub lesson.