AGP 2.0 spec (Vddq pins carry either 3.3 or 1.5V, depending on
which spec the card meets)
Vddq1.5 I/O Supply Voltage IMAX = 8.0A 1.425 1.575V (average currents <2A)
Vddq3.3 I/O Supply Voltage IMAX = 8.0A 3.15 3.45V (average currents <2A)
VCC3.3 3.3V Power Supply IMAX = 6.0A 3.15 3.45V
VCC5 5V Power Supply IMAX = 2.0A 4.75 5.25V
VCC12 12V Power Supply IMAX = 1.0A 11.4 12.6 V
AGP 3.0 spec
Vddq1.5 I/O Supply Voltage IMAX = 2.0A 1.425 1.575 V (1.0 amp average VDDQ)
VCC3.3 3.3V Power Supply IMAX = 6.0A 3.15 3.45 V
3.3VAUX 3.3V Aux IMAX = 0.375A 3.15 3.45 V
VCC5 5V Power Supply IMAX = 2.0A 4.75 5.25 V
VCC12 12V Power Supply IMAX = 1.0A 11.4 12.6 V
First off, you should have mentioned which voltage was out of
spec in Smart Doctor, and by how much. Another thing you could
do, is fire up Asus Probe and get a readout of the 3.3V, 5V, and
12V that come from the PSU.
Your new processor draws more current from +12V. On the old
power supplies, the entire primary side moves up and down, in
response to the load. The output voltages are established by
the turns ratio of the multiple secondary windings on the
output transformer. What this would normally mean, is if you
tug on +12V (more load), the voltage on +12V will fall, but
you will also get to see the +3.3V and the +5V rise. This is
a very handy trend, because when someone reports a problem in
this group, you can use the voltage trends to identify which
output on the ATX PSU has suddenly gotten an extra load.
To fix a voltage problem, there are several possible problems
and fixes:
1) The PSU could be inadequate for the current load being placed
on it. I recommend 12V@15A minimum for a P4 system with just
the basic components. There are web sites that allow a more
detailed calculation (
http://takaman.jp/D/?english but correct
the overcurrent for disk drives, as the numbers shown are at
spinup. Your disk manufacturer has the exact numbers, or use
[email protected] and 5V@1A for a modern, idling disk drive).
2) The PSU could be sick. Wavering voltages, or complaints
from Asus Probe about more than +/- 5% variation from
normal might be your first clue. You might even get a burning
smell just before it fails.
3) The ATX 20 pin power connector could be making bad contact
with the motherboard. There was one Asus motherboard, where
a bad batch of connectors did not make good contact with any
ATX supply that was plugged in. The ATX 20 pin should be pushed
into place, until the latch engages. The latch is there to make
sure it doesn't work itself loose. If the ATX 20 pin is allowed
to work loose, the pins heat up due to the partial contact,
they oxidize, and are permanently crippled. A low motherboard
power reading at this point, requires connector replacement to
permanently fix the problem. No amount of bandaid solutions will
work for more than a short time.
4) A partial short could be developing within the motherboard PCB.
This is uncommon. Also, a standoff in the wrong place, could
touch a copper power track on the bottom of the motherboard.
The "solder blob" problem on the P4C800 was another example
of a partial short affecting operation. This only affected
the initial production run.
So, get out Asus Probe or MBM5 and check the main voltages. With
the computer unplugged, pull the 20 pin connector and reseat it.
Check the plastic for signs of heat or melting. Make sure the latch
is fully seated. Post back what you find when reading both the
Smart Doctor screen and Asus Probe at the same time.
With some luck, all this will take is a power supply with a few
more amps on +12V.
Paul
