Overheating / 3.3 Voltage problems

[davewasmer]

Hey all,

Well, forgive me if the answer appears obvious, I am in a little over
my head.
I have an ASUS P4P800S motherboard with a P4 3.0 Ghz processor. I have
had no problems with my computer until the past couple days.

I came home recently to discover ASUS Probe (a hardware monitoring
program that came with the motherboard) open, warning my that my CPU
temperature was over the threshold (~65 C). I immediately pulled out
the case, opened it up to ventilate, and the temp dropped somewhat.

I then cleaned out the dust from the inside (a lot had accumulated). I
thought I had the problem solved. However, the temperature still seems
a little high, though not over threshold. All the fans are working.
Plus, now, under the "Voltage Monitor" screen, I am getting
warnings on occasion that the "3.3V" is outside of threshold
(10% deviation). I have no idea what this is. It seems to correlate
somewhat to when the CPU starts to run hot. You can smell it when the
temperature rises.

Any ideas on what this 3.3V is? Like I said, i have never had
problems, and my room has been much hotter than it is right now. I
just don't know what changed.

 

[Davej]

[...]
I came home recently to discover ASUS Probe (a hardware monitoring
program that came with the motherboard) open, warning my that my CPU
temperature was over the threshold (~65 C). I immediately pulled out
the case, opened it up to ventilate, and the temp dropped somewhat.

I then cleaned out the dust from the inside (a lot had accumulated). I
thought I had the problem solved. However, the temperature still seems
a little high, though not over threshold. All the fans are working.
Plus, now, under the "Voltage Monitor" screen, I am getting
warnings on occasion that the "3.3V" is outside of threshold
(10% deviation). I have no idea what this is. It seems to correlate
somewhat to when the CPU starts to run hot.

Well, it is possible that your power supply is dying and letting the
voltage get too high. That might be where the smell is originating.
Maybe you can borrow a voltmeter to measure the 3.3V? If the voltage
warning is bogus then you might have a problem with your cpu heatsink
or fan. You haven't changed any bios or overclock settings, right?

 

[Paul]

Hey all,

Well, forgive me if the answer appears obvious, I am in a little over
my head.
I have an ASUS P4P800S motherboard with a P4 3.0 Ghz processor. I have
had no problems with my computer until the past couple days.

I came home recently to discover ASUS Probe (a hardware monitoring
program that came with the motherboard) open, warning my that my CPU
temperature was over the threshold (~65 C). I immediately pulled out
the case, opened it up to ventilate, and the temp dropped somewhat.

I then cleaned out the dust from the inside (a lot had accumulated). I
thought I had the problem solved. However, the temperature still seems
a little high, though not over threshold. All the fans are working.
Plus, now, under the "Voltage Monitor" screen, I am getting
warnings on occasion that the "3.3V" is outside of threshold
(10% deviation). I have no idea what this is. It seems to correlate
somewhat to when the CPU starts to run hot. You can smell it when the
temperature rises.

Any ideas on what this 3.3V is? Like I said, i have never had
problems, and my room has been much hotter than it is right now. I
just don't know what changed.

On P4 boards, the processor Vcore circuit is powered from +12V,
via the 2x2 ATX12V connector.

The 3.3V on the board, may be regulated down by linear regulators,
for some of the lower voltage loads on the motherboard. Major
sources of load would be the 2.5V used by the DDR memory, or
similar or lower voltage levels used by the Northbridge or
Southbridge core logic.

If your 3.3V is dropping below normal, and you "smell heat" or something
getting hot, then it means something on the motherboard is getting
hot. It could be a component (check the temperature of the MOSFETs
near the DIMM slots). If the fault was a partial short inside the
PCB itself, then the motherboard might have a hot spot. With the
system running, feel around and see if something is hotter than it
should be.

The most extreme case I've heard of, is where some MOSFETs on a
motherboard of that era, got so hot, that the solder melted. So
if you are getting a smell, it could be something like that.

On my P4C800-E Deluxe motherboard, my board uses 3.3V @ 14A with
four sticks of RAM, and 3.3V @ 8.1A with just one stick of RAM.
The 14 amp number was with memtest86+ running, but I didn't run
memtest86+ for the single stick test.

The two symptoms you've detected go hand in hand. If the
3.3V was low, but there were no other symptoms, you could
laugh it off as a weak PSU. But if you "smell heat" and
have a low 3.3V, chances are the PSU is struggling to keep
up with a fault on the motherboard. In which case, if you
get lucky, you may be able to localise the fault by feeling
with your fingers, for a hot spot.

Paul

 

[DaveW]

Either your power supply unit or your motherboard is failing and losing
voltage stability. This can fry your CPU and other components. The easiest
thing to try first is to replace your PSU with a known working one and seeif
that fixes the problem. If not, it's most likely time for a new
motherboard.