CPU-fan issue


B

Bob Davis

A friend purchased a P35-DS3P mobo with two sticks of 1gb DDR2 RAM, a 3-pin
Coolermaster HSF, and a PCI-E video card to upgrade an older P4 478 system
in an ATX case. The PSU is a 480W Antec Truepower, and when everything is
connected the only response is a quick flicker of the CPU fan--no POST, no
PSU or case fans are spinning up, nothing. OTOH, when the CPU fan connector
(3-pin on the HSF, 4-pin on the mobo) is moved to a case-fan connector on
the mobo, it boots with no problem.

While this was connected, I connected the original Intel HSF (4-pin) to the
mobo's CPU-fan connector and although it still started fine the HSF
connected to the CPU-fan mobo connector (not attached to the CPU) would only
blip on every few seconds, never fully cranking up. I tried the same test
with an old 478 P4 HSF with a 3-pin connector and it would blip once, then
nothing. IOW, none of three HSF's (two 3-pin, one 4-pin) will work on the
mobo's CPU-fan connector.
We returned the first mobo thinking it was a mobo issue, presumably a bad
CPU-fan connector, but this second mobo is no different.
The 3-pin connector fits only one way with the guide on the mobo,
so I assumed the 3-pin-connector HSF's would work.

At this time it appears to function fine as long as the HSF is connected to
a case-fan connector on the mobo, but these seems make-shift to me. What am
I missing on this 4-pin CPU-fan connenctor issue?
 
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S

SteveH

Bob said:
A friend purchased a P35-DS3P mobo with two sticks of 1gb DDR2 RAM, a
3-pin Coolermaster HSF, and a PCI-E video card to upgrade an older P4
478 system in an ATX case. The PSU is a 480W Antec Truepower, and
when everything is connected the only response is a quick flicker of
the CPU fan--no POST, no PSU or case fans are spinning up, nothing. OTOH,
when the CPU fan connector (3-pin on the HSF, 4-pin on the
mobo) is moved to a case-fan connector on the mobo, it boots with no
problem.
While this was connected, I connected the original Intel HSF (4-pin)
to the mobo's CPU-fan connector and although it still started fine
the HSF connected to the CPU-fan mobo connector (not attached to the
CPU) would only blip on every few seconds, never fully cranking up. I
tried the same test with an old 478 P4 HSF with a 3-pin connector
and it would blip once, then nothing. IOW, none of three HSF's (two
3-pin, one 4-pin) will work on the mobo's CPU-fan connector.
We returned the first mobo thinking it was a mobo issue, presumably a
bad CPU-fan connector, but this second mobo is no different.
The 3-pin connector fits only one way with the guide on the mobo,
so I assumed the 3-pin-connector HSF's would work.

At this time it appears to function fine as long as the HSF is
connected to a case-fan connector on the mobo, but these seems
make-shift to me. What am I missing on this 4-pin CPU-fan connenctor
issue?

If its anything like the GA-P35C-DS3R I did for someone a while ago, you
might want to go into the BIOS and have a fiddle with the settings - it had
some odd default ones.

I also returned the board only to get the same problem on the new one.

As it happens the problem I initallly had was the same as yours, the CPU fan
flicked around a small bit and then nothing. It turned out it was the
memory. Read my answer to the post 'new build - no display on monitor' on
this group yesterday.

SteveH
 
B

Bob Davis

If its anything like the GA-P35C-DS3R I did for someone a while ago, you
might want to go into the BIOS and have a fiddle with the settings - it
had some odd default ones.

I also returned the board only to get the same problem on the new one.

As it happens the problem I initallly had was the same as yours, the CPU
fan flicked around a small bit and then nothing. It turned out it was the
memory. Read my answer to the post 'new build - no display on monitor' on
this group yesterday.

While troubleshooting this earlier I pulled the video card and memory with
no change. If the memory was bad it should've given multiple beeps, but not
even the PSU fans would crank up. I figured something was telling the PSU
to shut down within milliseconds of starting.

Update: The CPU HSF (Cooler Master) has a 3-pin connector while the mobo is
4-pin. When I connect the HSF to a case-fan connector on the mobo
everything spins up and it POST's just fine, but just won't work when that
Cooler Master HSF is connected to the CPU-fan connector. I heard some mobos
have a jumper to disable PWM, as maybe that's my problem, or like you
suggested maybe its in the BIOS.
 
S

SteveH

Bob said:
While troubleshooting this earlier I pulled the video card and memory
with no change. If the memory was bad it should've given multiple
beeps, but not even the PSU fans would crank up. I figured something
was telling the PSU to shut down within milliseconds of starting.

Update: The CPU HSF (Cooler Master) has a 3-pin connector while the
mobo is 4-pin. When I connect the HSF to a case-fan connector on the
mobo everything spins up and it POST's just fine, but just won't work
when that Cooler Master HSF is connected to the CPU-fan connector. I
heard some mobos have a jumper to disable PWM, as maybe that's my
problem, or like you suggested maybe its in the BIOS.

When I had the trouble I pulled the memory and go none of teh expected beeps
either. However, when I put one stick of memory in (as opposed to the
matched pair), it worked fine. I then got into the BIOS, adjusted the memory
voltage and all was well.
You should be able to turn off the PWM in the BIOS - once of course you can
get in!

SteveH
 
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B

Bob Davis

When I had the trouble I pulled the memory and go none of teh expected
beeps either. However, when I put one stick of memory in (as opposed to
the matched pair), it worked fine. I then got into the BIOS, adjusted the
memory voltage and all was well. You should be able to turn off the PWM
in the BIOS - once of course you can get in!

I got into the BIOS and disabled the "Smart CPU fan" function, and after
that it worked perfectly even when the HSF was plugged into the CPU-fan
connector. Oddly, when I later changed it back to enabled, the original
setting, it still worked and has been booting perfectly ever sense. I now
have XP loaded and no problems. I still don't know why it wouldn't POST
originally when the 3-pin HSF was connected to the CPU-fan connector on the
mobo.
 

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