"Dave" said:
I just got a new motherboard, an ECS 865PE-A. (Hope I won't regret not
getting something more expensive.) There is a heatsink over the
northbridge, and a connection for a northbridge cooling fan. Which was
new to me, because my old board didn't have either.
I'll never use the 800 mhz FSB speed, my CPU is an older P4 3.06 ghz,
and I don't intend to push any of the settings. Do you think I need to
buy a fan to supplement the heatsink? (My case is, I think, otherwise
well ventilated.) If so, how would I mount it? -- the manual says
nothing about the subject beyond mentioning the connection for it. I
don't recall seeing any holes or attachments in the area (but I forget
to double-check before I left home today.)
Also, the board reports "current system temperature." Measured where,
do you suppose?
Also, there are a few items in Setup that don't seem to have a reason
for being. For example, you can enable or disable Spread Spectrum.
Manual says, "If you enable spread spectrum, it can significantly
reduce the EMI (Electromagnetic Interference) generated by the system."
If there's a downside to choosing that, it seems like the manual ought
to say what that is, otherwise why would anyone *not* want that?
- Dave
The design intent here, is for the CPU cooler to "spill"
a little air over the fins of the Northbridge heatsink.
http://www.ixbt.com/mainboard/images/dual-chanel-apr04/865pe-a-board.jpg
If you were to, say, install a water block on the CPU, and water
cool the system, there would no longer be any spill from the
CPU cooler. The motherboard manufacturer cannot account for all
possible building styles.
My rule of thumb is, "if it burns you when you touch it,
stick a fan on it". The thinking goes, if the surface temperature
of the heatsink is 55C, you can only hold a finger on it for 2
seconds or less. Underneath the heatsink, the silicon die might be
25-30C hotter than that. That would be 85C. Some of that generation
of Northbridge, are rated for 99C max at the silicon die.
I had one system I worked on, a system with a special enclosure
and form factor (looks kinda like a laptop, only the motherboard
is behind the screen). The 865G Northbridge was in a virtually
insulated part of the enclosure. I stuck a digital thermometer on
it, and tested it. The Northbridge heatsink surface temperature
rose to 75C, before I shut things down. I ended up fitting a tiny
fan (maybe 40mm) to the heatsink, and after that, the surface temp
of the heatsink was only 37C and stable.
The best kind of heatsink for that, is a heatsink made with "ribs".
Heatsinks like that are extruded from aluminum. The ribs are quite
rigid, and a metal screw can be placed in the fan holes, and the
threads of the screw jam themselves nicely between the ribs. In fact
the outermost ribs on a heatsink like that, have a groove that is
wider than the inner ribs, explicitly so you can use metal screws.
(Since the screws chew tiny bits of aluminum off the heatsink,
it is a good idea to clean up all the metal filings when the job
is done. I have a miniature vacuum adapter kit for cleaning jobs
like that.)
The heatsink in the picture above, uses "fingers". The problem with
"fingers", is you cannot jam stuff between them, because they bend
like crazy. So screws would not be a good idea on your heatsink.
There are many ways to fit a fan. One thing to keep in mind, is
the Northbridge heatsink cannot take a lot of stress. You cannot
man-handle the thing, as it may separate from the chip. The chip
itself cannot take too much "normal" or "down" force, without
cracking the silicon die directly underneath the thing. If you
cannot use screws to hold the fan in place, then the fan should be
suspended from something other than the heatsink, so you don't mess
it up.
So, fit your retail Intel CPU heatsink/fan, fire up the system,
and see how hot the fins get on the Northbridge. You can start
by just using the BIOS as your test case. If it gets too hot, shut
off the system and work out a better cooling solution. Feel for air
flow, and see if any air is coming from the CPU cooler. It may
turn out you have nothing to worry about.
In a couple of systems here, I've taken a piece of aluminum
angle iron, drilled one hole in it, and placed a screw through
it to one of the PCI slot covers. That gives me a platform to hold
a fan with. I use nylon tie-wraps to fasten a fan to the piece of
aluminum. I use that to provide extra cooling for a video card.
There are commercial equivalents of that same concept, basically
a bracket that bolts to the PCI slot cover screw holes. If you
had to, you could mount a fan on one of those.
*****
The current system temperature or "case" temperature, is supposed
to be representative of the air temperature inside the computer
case. The sensor should not be near any hot components. If room
temperature is 25C, then the computer case air temp would be 32C
if the computer case was well cooled. Knowing the case air
temperature, gives you a rough idea as to how hard a time
you are giving your hard drives.
Hard drives are sensitive to temperature and humidity. A disk
drive is not hermetically sealed, and has a breather hole. That
means, after a while, the outer atmospheric conditions influence
the guts inside the drive. (The breather hole is there to
equalize the pressure difference between atmospheric pressure
and pressure inside the drive. Barometric pressure is changing
all the time, so a tiny air stream is constantly moving in and
out of the drive.)
(This company makes breather holes for disk drives.)
http://www.donaldson.com/en/diskdrive/support/datalibrary/000610.pdf
As the air becomes more humid, the allowed max temperature of the
metal on the hard drive drops. At 60% R.H., the max temp is about
35C. If your computer room is air conditioned, the air will be
about 40% R.H. The computer case can get a bit warmer, if the
air is dry. However, if you live in a room without air conditioning,
it is easy for the air to get to 60% relative humidity (carpets
start to mildew at 60%, if you don't have a humidity meter).
So, knowing the computer case air temperature, and the environment
you are working in, can give you some advance warning as to whether
you are abusing your hard drive. On some hard drives, you can
actually read the hard drive temp via SMART. Or use a digital
thermometer and stick the sensor on the top of the hard drive
casing.
While the hard drive won't die over night with a bit of abuse
from heat and humidity, it won't take too long. I managed to
kill a Maxtor hard drive while my central air was off for a
month, and it was a bit more than 60% humidity at the time.
So that should give you some idea why you would want to know
what the case temperature is like.
*****
Spread spectrum can be "center spread" or "down spread". In
center spread, the frequency varies both above and below
the nominal value. Since the time average of the modulation
has the same value of frequency, as the original clock
value, no performance is lost.
If you have "down spread", the frequency varies from nominal
to a frequency below nominal. The average of that is slightly
less than your normal performance level.
Center spread affects your max overclock. The largest positive
deviation above center frequency, could cause you to crash if
you are on the bleeding edge.
On down spread, there is no such worry. With down spread turned
on or off, the same max overclock applies. But you have that
slight performance loss caused by the time average of the down
spread, being less than your previous nominal clock.
Summary: If you are an overclocker, turn it off
If you are not an overclocker, leave the spread turned on.
HTH,
Paul
