P4C800-E Delux Power-On Problems

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Bringer

I have a P4C800-E Deluxe motherboard here that refuses to power on when an
my AGP card (PNY Geforce4 TI4400) is plugged in. When the card is
unplugged the system will power on fine. The board has already been RMA'd
once for this problem and they said it was a 'bad flash' so before I call
them back and give them a royal piece of my mind I wanted to check here to
see if anyone had any ideas what could be going on. So do anyone?

Bringer
 
Bringer said:
I have a P4C800-E Deluxe motherboard here that refuses to power on when an
my AGP card (PNY Geforce4 TI4400) is plugged in. When the card is
unplugged the system will power on fine. The board has already been RMA'd
once for this problem and they said it was a 'bad flash' so before I call
them back and give them a royal piece of my mind I wanted to check here to
see if anyone had any ideas what could be going on. So do anyone?

Bringer
Click to expand...

Around the time of the P4B motherboard (S478/SDRAM), a circuit was
added to the AGP slot, called "AGP_Warn". (AGP_Warn is the word printed
right next to the circuit.) The logic for AGP_Warn says:

IF (AGP_Card_Inserted & TYPEDET_Sez_3.3V_only_Video_Card)
THEN stop_computer_from_powering_up

That circuit prevents some really old, incorrectly keyed video
cards from blowing up a 1.5V only Northbridge with 3.3 volts.

The first round of implementations, included a Red LED next to the
AGP slot. If the Red LED lit up, you then knew that a bad video card
was being used. (And you also knew for sure, why the computer would
not power up.)

In the second round, the LED was removed to save cost. The word
"AGP_Warn" could still be seen printed next to the AGP slot, so
you knew the circuit was still there. You could not absolutely
and for sure, know it was there, because the LED was not populated.
There were still holes in the board for the LED.

I had a look at my P4C800-E, and I really don't see any signs
of the circuit. It could still be there, but just not placed on
the motherboard in the same way as was done previously. (When the
transistors for the circuit are spread around the board, it won't
be possible to recognize the form of the circuit block any more.)

In terms of the implementation, pg.50 of this doc shows the pinout.
TYPEDET# signal is on pin 2A (I believe that is on the back side of
the card). A proper modern video card should ground pin 2A. With
an ohmmeter, you should see a direct short between pin 2A and 5A.

http://web.archive.org/web/20030314...m/technology/agp/downloads/agp30_final_10.pdf

Now, some manufacturers have what are called "testability engineers".
At the factory, these guys make sure the circuit board designs are
modified, so that the circuit board can be tested. It appears that
some of them have added a resistor to the video card, that runs from
pin 2A to ground. If, when using the ohmmeter, you read a reasonably
small but finite resistance (say 50 ohms to 150 ohms or so), it
could be that was added for testing. But, what such a resistor can
do, is foul up the Asus "AGP_Warn" circuit. Also, in cases other
than Asus, I understand the inclusion of that resistor, has caused
some motherboard AGP regulators, to produce voltages inappropriate
for running the logic - AGP is supposed to be 1.5V or 3.3V, and a
video card with a resistor on pin 2A, can cause the Vreg on the
motherboard to deliver 2.x volts instead, which is good for
neither purpose.

So, before giving anyone heck, I would grab another AGP card and
try it in the AGP slot. Not a 3.3V only card of course (it won't
fit in the slot anyway).

If another AGP card works, but the PNY continues to stop it, you
can return the PNY for your money back (as an RMA is only going
to give the same problem). If you own a multimeter, you could
take a stab at measuring the resistance between pin 2A and 5A
on the video card, to see if there is a dead short (as defined by
the standard), or a low value resistor (as defined mistakenly by
test engineering).

Just a guess,
Paul
 
(e-mail address removed) (Paul) wrote in
Around the time of the P4B motherboard (S478/SDRAM), a circuit was
added to the AGP slot, called "AGP_Warn". (AGP_Warn is the word
printed right next to the circuit.) The logic for AGP_Warn says:

IF (AGP_Card_Inserted & TYPEDET_Sez_3.3V_only_Video_Card)
THEN stop_computer_from_powering_up

That circuit prevents some really old, incorrectly keyed video
cards from blowing up a 1.5V only Northbridge with 3.3 volts.

The first round of implementations, included a Red LED next to the
AGP slot. If the Red LED lit up, you then knew that a bad video card
was being used. (And you also knew for sure, why the computer would
not power up.)

In the second round, the LED was removed to save cost. The word
"AGP_Warn" could still be seen printed next to the AGP slot, so
you knew the circuit was still there. You could not absolutely
and for sure, know it was there, because the LED was not populated.
There were still holes in the board for the LED.

I had a look at my P4C800-E, and I really don't see any signs
of the circuit. It could still be there, but just not placed on
the motherboard in the same way as was done previously. (When the
transistors for the circuit are spread around the board, it won't
be possible to recognize the form of the circuit block any more.)

In terms of the implementation, pg.50 of this doc shows the pinout.
TYPEDET# signal is on pin 2A (I believe that is on the back side of
the card). A proper modern video card should ground pin 2A. With
an ohmmeter, you should see a direct short between pin 2A and 5A.

http://web.archive.org/web/20030314013601/http://developer.intel.com/te
chnology/agp/downloads/agp30_final_10.pdf

Now, some manufacturers have what are called "testability engineers".
At the factory, these guys make sure the circuit board designs are
modified, so that the circuit board can be tested. It appears that
some of them have added a resistor to the video card, that runs from
pin 2A to ground. If, when using the ohmmeter, you read a reasonably
small but finite resistance (say 50 ohms to 150 ohms or so), it
could be that was added for testing. But, what such a resistor can
do, is foul up the Asus "AGP_Warn" circuit. Also, in cases other
than Asus, I understand the inclusion of that resistor, has caused
some motherboard AGP regulators, to produce voltages inappropriate
for running the logic - AGP is supposed to be 1.5V or 3.3V, and a
video card with a resistor on pin 2A, can cause the Vreg on the
motherboard to deliver 2.x volts instead, which is good for
neither purpose.

So, before giving anyone heck, I would grab another AGP card and
try it in the AGP slot. Not a 3.3V only card of course (it won't
fit in the slot anyway).

If another AGP card works, but the PNY continues to stop it, you
can return the PNY for your money back (as an RMA is only going
to give the same problem). If you own a multimeter, you could
take a stab at measuring the resistance between pin 2A and 5A
on the video card, to see if there is a dead short (as defined by
the standard), or a low value resistor (as defined mistakenly by
test engineering).

Just a guess,
Paul
Click to expand...

I had read this before, but the thing that has me ticked is they said it
will work and it doesn't. The card can't be returned. It's a well used
card I picked up years ago, and I honestly can't see the point of buying
another card when I don't game anymore. That and the fact that at this
point I can't afford to buy another card.

According to the info on http://www.ertyu.org/
~steven_nikkel/agpcompatibility.html the card is keyed universally (1.5
and 3.3) so I can't see why it wouldn't work (unless, of course the
agpwarn circuit is being tripped). Then that brings me to the question
is there a way to bypass that circuit. Then again, if it is indeed the
problem ASUS will get it from me for the simple fact they flat out lied
to me.

Just out of curiousity do other manufacturers implement this circuit?
I've also got an abit ic7-g board and the card works fine in there so if
that board has the circuit I'd gather there's something weird about the
Asus implementation.

At anyrate thanks for the lengthy explanation. I appreciate it if for
nothing more than the educational value.

Bringer
 
Bringer said:
(e-mail address removed) (Paul) wrote in


I had read this before, but the thing that has me ticked is they said it
will work and it doesn't. The card can't be returned. It's a well used
card I picked up years ago, and I honestly can't see the point of buying
another card when I don't game anymore. That and the fact that at this
point I can't afford to buy another card.

According to the info on http://www.ertyu.org/
~steven_nikkel/agpcompatibility.html the card is keyed universally (1.5
and 3.3) so I can't see why it wouldn't work (unless, of course the
agpwarn circuit is being tripped). Then that brings me to the question
is there a way to bypass that circuit. Then again, if it is indeed the
problem ASUS will get it from me for the simple fact they flat out lied
to me.

Just out of curiousity do other manufacturers implement this circuit?
I've also got an abit ic7-g board and the card works fine in there so if
that board has the circuit I'd gather there's something weird about the
Asus implementation.

At anyrate thanks for the lengthy explanation. I appreciate it if for
nothing more than the educational value.

Bringer
Click to expand...

There is good reason to have a circuit like that, as it prevents
burned motherboards. In fact, when I bought my P4B motherboard, I
insisted on finding a revision 1.05 board, as that was the first
board with the protection circuit in place. In terms of the standards,
if all video card manufacturers had followed the rules as defined
in the standards in the first place, this circuit would not have
been necessary. The circuit protects against "non-compliant"
video cards, that have the slots cut in the edge card incorrectly.

The fact that your card is keyed universal here, is not the issue.
There are many failure modes possible, but most of those would
be eliminated by virtue of the fact that your video card works
fine in another motherboard. That leaves:

1) Assuming there is an AGP_Warn circuit on the P4C800-E (and I
cannot even be sure of that, due to not being able to find
the block of circuitry), the defect could be in that circuit.
There have been cases before that tended to suggest that was
the problem (i.e. motherboards where the first generation Red
LED equipped circuit was always lit, implying the circuit
tripped for no reason). If a motherboard had an AGP_Warn and
it was defective, then possibly no AGP video card would work.
If some video cards work and some don't, that leaves...

2) The second potential defect is with the video card itself.
The standards say TYPEDET# should be a direct connection to
ground. If the video card manufacturer insists on placing
a resistor between TYPEDET# and GND on a 1.5V video card,
then that is not strictly speaking, compliant with the spec.

I am not going to suggest a hack you could attempt, because
I don't believe you can afford to blow out both the motherboard
and the video card, if it doesn't work. I think if you use your
imagination, you can think of that hack. If you are rich and
carefree, you could attempt it.

Normally, I would recommend taking this up with the video card
manufacturer (or get out your ohmmeter). But in the case of
PNY, I doubt you'd get a response.

TYPEDET# is not intended to be a dynamic signal. It should either
be an open circuit with respect to ground, or it should be a
short to ground. When it is shorted to ground, it is telling
the motherboard that it "prefers to run at AGP 1.5V". The
universal keying of your card, means if it runs into a motherboard
that only supports 3.3V AGP I/O, it will "tolerate" the situation.
In the case of your motherboard, the AGP slot only runs at 1.5V
supply voltage, as you can see in the manual.

Note - in my description above, there is no mention of 0.8V. The
I/O _supply_ pins on a video card are either given 1.5V or 3.3V.
The signal pins themselves, can operate at 0.8V, 1.5V, or 3.3V.
So, in terms of I/O supply voltage compliance, the TYPEDET# pin
only needs to signal whether 1.5V or 3.3V is appropriate. A
GPU supplied with a 1.5V I/O supply voltage, can then make 0.8V
or 1.5V sized I/O signals, as it desires.

Paul
 
surely you could do a swap somewhere locally?

Bringer said:
(e-mail address removed) (Paul) wrote in


I had read this before, but the thing that has me ticked is they said it
will work and it doesn't. The card can't be returned. It's a well used
card I picked up years ago, and I honestly can't see the point of buying
another card when I don't game anymore. That and the fact that at this
point I can't afford to buy another card.

According to the info on http://www.ertyu.org/
~steven_nikkel/agpcompatibility.html the card is keyed universally (1.5
and 3.3) so I can't see why it wouldn't work (unless, of course the
agpwarn circuit is being tripped). Then that brings me to the question
is there a way to bypass that circuit. Then again, if it is indeed the
problem ASUS will get it from me for the simple fact they flat out lied
to me.

Just out of curiousity do other manufacturers implement this circuit?
I've also got an abit ic7-g board and the card works fine in there so if
that board has the circuit I'd gather there's something weird about the
Asus implementation.

At anyrate thanks for the lengthy explanation. I appreciate it if for
nothing more than the educational value.

Bringer
Click to expand...
 
Unfortunatly no. Only have 2 PCs and the other acts as a server so it's
just using the onboard video. Only spare cards I have to swap with are a
1MB PCI that's old as all hell (obviously) and a viper v550. The latter
won't work and the former would require a spare PCI slot, which I don't
have.

Bringer
 
I was meaning a local PC use group or some such.

Bringer said:
Unfortunatly no. Only have 2 PCs and the other acts as a server so it's
just using the onboard video. Only spare cards I have to swap with are a
1MB PCI that's old as all hell (obviously) and a viper v550. The latter
won't work and the former would require a spare PCI slot, which I don't
have.

Bringer
Click to expand...
 
To the average Joe around here a computer is some fantasy thing out of
one of those silent films. :P

Bringer
 
Oh dear.
I'd send you an old spare except it woud cost me much more than the card is
worth for the mail... (south pacific)

Guess that makes you the local guru then :) Not much help sorry.
 
Unfortunately, yes. Got to <sarcasm>love</sarcasm> the wonderful
assumption "oh you know computers, fix mine!"
 
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