Muffled sound P4P800 (heat)

[Guest]

Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

After playing a game for 20 minutes, the sound changes and is not crisp
anymore. So, I have to increase volume.

I have Audigy2 ZS on my P4P800 deluxe and have disabled the on-board audio
in the bios.
Before getting my Audigy sound card, I used the on-board audio and I had the
same problem even then!
Because sound changes after playing a game for a while, I am assuming this
is a heat problem.
Am I wrong?

My speaker system is Logitech Z-640.

What is heating up that causes this?
I need to know to improve its cooling.

Motherboard Monitor shows the CPU (P4C 2.6 @3.17) and case temperatures to
be at 30 and 34 at idle and at 41 and 37 under load.

Thanks,

Navid

 

[Guest]

Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

Paul wrote:
> I've noticed at least two MOSFETs on my P4C800-E get hot. I
> checked them with a thermistor, and the surface temperature is
> about 45C when room temp is 25C. If you hold a finger on them,
> they get even hotter, because of the insulating effect of your
> finger. 45C is not hot enough to affect the reliability of
> them, but I cannot say I'm impressed with that design. If that
> circuit is in fact a regulator circuit, a switching design would
> cost a few dollars more, but would be cool to the touch.

If you're referring to the MOSFETs providing the core voltage to the
CPU, they will be a switching setup - the current draw is far too high
(approaching 100 amps on some CPUs) for a linear regulator.

--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/

 

[Paul]

Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

In article <ovutd.460886$%k.222203@pd7tw2no>, Robert Hancock
<hancockr@nospamshaw.ca> wrote:

> Paul wrote:
> > I've noticed at least two MOSFETs on my P4C800-E get hot. I
> > checked them with a thermistor, and the surface temperature is
> > about 45C when room temp is 25C. If you hold a finger on them,
> > they get even hotter, because of the insulating effect of your
> > finger. 45C is not hot enough to affect the reliability of
> > them, but I cannot say I'm impressed with that design. If that
> > circuit is in fact a regulator circuit, a switching design would
> > cost a few dollars more, but would be cool to the touch.
>
> If you're referring to the MOSFETs providing the core voltage to the
> CPU, they will be a switching setup - the current draw is far too high
> (approaching 100 amps on some CPUs) for a linear regulator.

No, these are over near the DIMMs. In fact, the MOSFETs for Vcore
have always been cool on the Asus boards I've got here. The only
exception was when I put a Tualatin 1.4GHz in my P2B-S, and then
the Vcore MOSFETs started to get warm.

Of the three MOSFETs near the DIMMS on the P4C800-E, one seems to
be a linear for the DIMMs, making 2.5V from 3.3V. At least the
MOSFET had 2.5V on one pin, and 3.3V on the other.

The only function I can think of for the two hot ones, is a
push-pull linear regulator for the DIMM terminator voltage.
In the example below, is a circuit for SSTL2 termination, and
maybe that is used on DDR ? The 1.25V "power supply" must on
a per cycle basic, either source or sink current, depending
on how many ones and zeros there are on the 128 data plus 16 ECC.
This means the termination power supply is different than your
average conversion problem, as both sourcing and sinking is
required. Now, normally, you can get some tiny regulator chips
to do this (and you'd need a few to handle that many data bits),
but as Asus are penny pinchers, maybe these two MOSFETs are
doing a big version of the same thing. I cannot see any
magnetics near the two MOSFETS, and the main magnetics
are one entry choke near the 2x2 +12V power connector, plus
three output inductors for the three phase Vcore. Basically
the MOSFETs would be part of a 1.25V linear power amp.

1.25V
+2.5V | +2.5V memory termination
| Rterm | times about 144
|\ | |\ instances. Vterm must
--| \----Rseries---+----| \-- sink or source current,
|/ |/ at least as drawn here.
| |
GND GND
(e.g. Northbridge) (e.g. memory chip)

(from http://download.micron.com/pdf/misc/sstl_2spec.pdf )

Asus likes to use quad op amps and these MOSFETS. The 14 pinner
near the MOSFETs is a quad op amp. If you look at page 21 of:

http://www.asuscom.de/pub/ASUS/mb/sock478/P4C800E-DX/f1347_p4c800-e_deluxe.pdf

the two hot MOSFETs are the ones below the right most pair of
DIMMs.

Paul