Archived from groups: alt.comp.periphs.mainboard.asus (
More info?)
"Paul" <nospam@needed.com> wrote in message
news:nospam-1207042305460001@192.168.1.177...
> In article <x8GIc.117843$wH4.6482760@twister.southeast.rr.com>, "Navid"
> <nospam@nospam.invalid> wrote:
>
>> There are 2 FET transistors on P4P800 deluxe motherboard between the AGP
>> and
>> the adjacent PCI slot. They get extremely hot. Sometimes to the extent
>> that my CPU (P4C 2.6G) throttles down! The motherboard in that area gets
>> pretty hot too.
>>
>> Has anybody else noticed high temperature of those transistors or is
>> something wrong with my motherboard?
>>
>> Thanks,
>>
>> Navid
>
> There is a MOSFET next to the word "PCI 1", as pictured in
> the P4P800 Deluxe manual E1323. It seems to have +5V around it,
> and I don't know why Asus would need to make a switch or a
> linear regulator out of a MOSFET connected to such a high
> voltage.
>
> Following over to the right, are two MOSFETs and a toriod with
> a large number of turns of copper wire on it. This is a switching
> regulator, making 2.5V for the DIMMs. The 2.5V copper "island"
> flows back to the left on the board, and appears to be feeding the
> Northbridge, and also seems to feed the second hot MOSFET you
> mention. My guess is, this could be a linear regulator, dropping
> from 2.5V to 1.5V for the AGP slot. That MOSFET is the one on the
> right hand end of the AGP slot.
>
> Feel both the MOSFETs and other components in the area, as the
> heat could be originating from just one component, but flowing
> through the general area. If both MOSFETs are hot, then either
> the two MOSFETs are connected to a common circuit, and both
> have been enabled at the same time, instead of just one of them.
> You might be able to reduce the heat on the MOSFET next to the
> AGP slot, by going into the BIOS and raising the AGP I/O voltage,
> and them go to the Vdimm and drop Vdimm to 2.6V (just enough to
> run PC3200 RAM). Dropping Vdimm and raising Vagp, reduces the
> voltage drop across the MOSFET next to the right hand end of
> the AGP slot, and since P=V*I, the power should be reduced
> as well.
>
> Unless you can get confirmation from other users of this
> board, that the heat is "normal", I'd try an RMA. MOSFETs
> have a safe operating zone, and the hotter they get, the higher
> the resistance of the MOSFETs become. I doubt the MOSFETs
> were ever intended to get that hot.
>
> Maybe this could be caused by a defective AGP card. If you have
> another compatible AGP card handy, try swapping it in and see how
> hot your MOSFETs get. Since only I/O pads are supposed to be
> powered by I/O voltages, the power consumption through the MOSFETs
> should be in the same ballpark, for two different AGP8X video card
> designs.
>
> Paul
Thanks Paul,
I have already ordered a cheap PCI graphics card to make sure it is not my
VGA 9600 card.
Is there a way to measure the P4 current to make sure that the CPU is not
faulty (drawing too much current). I even considered ordering a cheap
Celeron. But, I thought I ask here first if there is another (cheaper) way.
Navid
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