A8N-SLI and FX-55 CPU Temps

[Kevin Mayer]

Greetings,

I have an ASUS A8N-SLI and FX-55. My CPU Temps seem to be on the high
side. After running future mark 05, temps were at 58c. At idle, temps
are about 45c. Room temp was about 67f. I have a Silverstone SST-TJ03-S
case, and Swiftech MCX6400-V Heatsink with Enermax UC-8FAB-B(N) Heatsink
Fan. The system has been up and running about six months, and has never
crashed. None the less, I think max temp for this CPU is 63c, and I'm
concerned. What do you suggest?

 

[Paul]

Greetings,

I have an ASUS A8N-SLI and FX-55. My CPU Temps seem to be on the high
side. After running future mark 05, temps were at 58c. At idle, temps
are about 45c. Room temp was about 67f. I have a Silverstone SST-TJ03-S
case, and Swiftech MCX6400-V Heatsink with Enermax UC-8FAB-B(N) Heatsink
Fan. The system has been up and running about six months, and has never
crashed. None the less, I think max temp for this CPU is 63c, and I'm
concerned. What do you suggest?

Did you look at the performance curves on the Swiftnet.com page ?

One web site I glanced at, says the Enermax UC-8FAB-B is 25-40CFM.
The curve for the MCX6400-V, says theta_R is 0.29 C/W at 25CFM, and
0.21 C/W at 40 CFM. You could try a 60CFM fan, which will bring you
down to 0.18 C/W. The processor power dissipation times theta_R
gives the temperature rise above case air temp.

http://www.swiftnets.com/products/mcx6400-V.asp

According to amdcompare.com, the FX-55 has a TDP of 104W. If your
theta_R was 0.21, that would give a 21.8C rise in temp, over the case
air temp. Is your computer case air temp 36C ?

Amdcompare.com lists 65C as the max temp for the processor. Yet the
30430.pdf document from amd.com, lists 63C as the max case temp.

Now, one thing the Swiftech products have, is a thick base.
This should give excellent heat spreading properties. It should
also allow you to sanity check the temperature measurement, by
putting your finger on the base of the heatsink. Is the thing
boiling hot ? If not, the measured temperature could be in error.
(I assume you have some thermal paste on there.)

Options:

1) Don't worry about it. It could be a measurement error, and it
isn't all the way to 63C yet.
2) Improve computer case ventilation. Each degree C drop in the
case temp, drops the CPU heatsink a degree as well. A 7C to 10C
rise in case temp versus room temp, is a reasonable target range.
3) Experiment with yet more heatsinks. Popular ones are
XP-90C, XP-120, Big Typhoon, Zalman CNPS9500. You'll have to
check each one for theta_R, mechanical compatibility, whether
it supports S939 or needs an extra adapter, and so on. The
CNPS9500 is rated theta_R of 0.12C/W to 0.16C/W, depending on
the fan controller setting. Downside of the CNPS9500, is the
first batch does not have a perfectly flat base, and some
reviewers have been lapping the base for best performance.
Considering the price of the CNPS9500, most users would
expect better quality than that.

Paul

 

[Kevin Mayer]

Thanks for the input Paul. You must be a thermal engineer with that kind
of knowledge. I'm not sure what the caes temp is. Is the case temp taken
inside the case or outside?

When I put my finger on the heatsink, it does not feel hot to me at 48c.
Warm, but not hot. No problem keeping my finger on it as long as I want.
I have the fan blowing down onto the heatsink not away from it. I assume
this is correct.

When I take the side of the case off, the temperatures drop down to 38c.

Thanks for all your help.

Kevin

 

[RonK]

I see on the Silverstone web page that the case you has comes with a 120mm
front fan and 2 80mm rear fans and an 80mm top fan. Are all the fans
running ?
Are you using any fan control programs like fanspeed, motherboard monitor
etc?
Did you change any fan speed settings in bios ?

 

[Paul]

Thanks for the input Paul. You must be a thermal engineer with that kind
of knowledge. I'm not sure what the caes temp is. Is the case temp taken
inside the case or outside?

When I put my finger on the heatsink, it does not feel hot to me at 48c.
Warm, but not hot. No problem keeping my finger on it as long as I want.
I have the fan blowing down onto the heatsink not away from it. I assume
this is correct.

When I take the side of the case off, the temperatures drop down to 38c.

Thanks for all your help.

Kevin

There should be a "motherboard temperature" reading somewhere. That
is the computer case air temperature. If you experience a big temp
drop when opening the side on the computer, it means you need to move
more cool room air through the computer case. The difference between
the motherboard temperature reading and the room air temperature,
is supposed to be no more than about 7C to 10C. If the air in the
case is getting hotter than that, it is likely not doing your
disk drives any good.

To review what kinds of temps I would expect.

Room temp 67F = 19.4C
Allowed case temp rise 7C more --> +7
------------------ -----
Measured case air temp 26.4C
Heat sink temp rise 104W @ 0.21C/W 21.8C
------------------ -----
CPU resulting temp 48.2C

If the case air is rising more than 7C, it might be cheaper to work
on reducing the case air temperature, than trying to reduce theta_R
of the heatsink.

A computer case needs at least one fan, other than the fan in the
PSU. Most of my computers have two, one in the front and one in the
back. In the case of my Sonata (original, not Sonata II), I removed
the plastic grill in the front and the air filter, to get a decent
drop in case air temperature. Sometimes, the fans are sufficient,
but are starved due to insufficient vent area.

Hmmm. The back looks pretty good.

http://www.silverstonetek.com/products/tj03/back view/tj03.jpg

The interior doesn't look bad.

http://www.silverstonetek.com/products/tj03/interior/tj03.jpg

But perhaps the filter and airflow path around the front fan
area is the problem. It doesn't look like it would be easy to
remove the lower plastic bezel on that case, as the buttons
are on there.

http://www.silverstonetek.com/products-tj03.htm

Paul

 

[Kevin Mayer]

Hi Ron,

All fans are running and no fan control is in place. I did not change
any fan speeds in bios. Thanks.

Kevin

 

[Kevin Mayer]

There should be a "motherboard temperature" reading somewhere. That
is the computer case air temperature. If you experience a big temp
drop when opening the side on the computer, it means you need to move
more cool room air through the computer case. The difference between
the motherboard temperature reading and the room air temperature,
is supposed to be no more than about 7C to 10C. If the air in the
case is getting hotter than that, it is likely not doing your
disk drives any good.

To review what kinds of temps I would expect.

Room temp 67F = 19.4C
Allowed case temp rise 7C more --> +7
------------------ -----
Measured case air temp 26.4C
Heat sink temp rise 104W @ 0.21C/W 21.8C
------------------ -----
CPU resulting temp 48.2C

If the case air is rising more than 7C, it might be cheaper to work
on reducing the case air temperature, than trying to reduce theta_R
of the heatsink.

A computer case needs at least one fan, other than the fan in the
PSU. Most of my computers have two, one in the front and one in the
back. In the case of my Sonata (original, not Sonata II), I removed
the plastic grill in the front and the air filter, to get a decent
drop in case air temperature. Sometimes, the fans are sufficient,
but are starved due to insufficient vent area.

Hmmm. The back looks pretty good.

Hi Paul,

The mobo temp reading was at 36c when the CPU was reading 48c. I say was
because you solved the problem. Fortunately, removing that front bezel
is actually pretty easy. The filter consists of a tightly woven material
and a larger mesh screen. I can also leave that front door open for even
less air restriction. At the moment, I have just the larger mesh screen
in place (to keep the dog hair out hopefully) and the door open. CPU is
now 39c and MB is 25c. Those numbers are much more comforting than
before. What do you think, about what you would expect? It should be
noted that it has only been in this current circulation state for about
45 minutes.

 

[GSV Three Minds in a Can]

Bitstring <[email protected]>, from

The mobo temp reading was at 36c when the CPU was reading 48c. I say was
because you solved the problem. Fortunately, removing that front bezel
is actually pretty easy. The filter consists of a tightly woven material
and a larger mesh screen. I can also leave that front door open for even
less air restriction. At the moment, I have just the larger mesh screen
in place (to keep the dog hair out hopefully) and the door open. CPU is
now 39c and MB is 25c. Those numbers are much more comforting than
before. What do you think, about what you would expect?

Those temps are fine. The 'fine screen' filters are useless, unless you
have a 747 turbine driving the airflow (look under a semiconductor Fab
some time!) - if the dust goes in through the front fan (rather than
sucked through the CD/Floppy door slots) you can ignore it for 2 years,
then vacuum it off the heatsinks (I never bother). As you note, dog/cat
hair, fluff, and bits of silver foil, do need stopping somehow, and the
coarse filters work fine - inspect quarterly, rinse under tap if
required (assuming it's the normal coarse plastic mesh stuff).

The sort of axial fans used in PC cases can move a lot of air, but are
defeated by even a tiny amount of resistance/back pressure (I mean a
couple of mm of Hg) which is why filters, and even the 'stamped out'
sort of fan openings (as opposed to proper wire grilles), are such a
problem. If you want serious (vacuum cleaner) suck/blow, you use a
different fan design.

 

[Paul]

Hi Paul,

The mobo temp reading was at 36c when the CPU was reading 48c. I say was
because you solved the problem. Fortunately, removing that front bezel
is actually pretty easy. The filter consists of a tightly woven material
and a larger mesh screen. I can also leave that front door open for even
less air restriction. At the moment, I have just the larger mesh screen
in place (to keep the dog hair out hopefully) and the door open. CPU is
now 39c and MB is 25c. Those numbers are much more comforting than
before. What do you think, about what you would expect? It should be
noted that it has only been in this current circulation state for about
45 minutes.

39C sounds pretty good

Paul

 

[Pete M Williams]

Bitstring <[email protected]>, from the
wonderful person Kevin Mayer <[email protected]> said


you can ignore it for 2 years, then vacuum it off the heatsinks (I never
bother).

Please be very careful inserting a vacuum cleaner nozzle inside a PC due to
the fact that most are plastic and therefore possibly highly charged with
static electricity.
A can of compressed air is the preferred method of cleaning the heatsink
fins.

 

[GSV Three Minds in a Can]

Bitstring <[email protected]>, from

Please be very careful inserting a vacuum cleaner nozzle inside a PC due to
the fact that most are plastic and therefore possibly highly charged with
static electricity.

Not in this climate, son!

A can of compressed air is the preferred method of cleaning the heatsink
fins.

That just chucks the dust around - I've never had any trouble using a
vacuum cleaner with a brush attachment - but as I mentioned I don't
usually bother.

 

[milleron]

Bitstring <[email protected]>, from


Not in this climate, son!


That just chucks the dust around - I've never had any trouble using a
vacuum cleaner with a brush attachment - but as I mentioned I don't
usually bother.

Pete is absolutely correct about the possibility of IC-frying static
discharge from a plastic nozzle on a vacuum. It's true that the
compressed air blows the dust around, but it gets it off of critical
parts where it can interfere with heat exchange, and it's safe to use
inside a computer. I've read the advice of one authority who says he
does use vacuums inside PCs but only with steel nozzles that have a
wire soldered to them that he can alligator clip to the computer's
power supply.

Ron

 

[GSV Three Minds in a Can]

Pete is absolutely correct about the possibility of IC-frying static
discharge from a plastic nozzle on a vacuum.

=Possibility= is the key word. There is also the possibility of static
build-up in the plastic nozzles of compressed air cans. I've never
suffered from that one either, but Google will find it for you.

<snip>

 

[Pete M Williams]

Not in this climate, son!

But not everyone lives in your climate, daughter!

You have to remember that people from all over the world use this group.
These people are of varying degrees of computer competence also.
For someone to suggest that it is safe to use a vacuum nozzel inside a PC
because they have done it a few times is irresponsible at the very least.

I've never had any trouble using a vacuum cleaner with a brush attachment

Said the vicar to the nun. ;-)

 

[GSV Three Minds in a Can]

Bitstring <[email protected]>, from

But not everyone lives in your climate, daughter!

True. Some places are even damper.

You have to remember that people from all over the world use this group.
These people are of varying degrees of computer competence also.
For someone to suggest that it is safe to use a vacuum nozzel inside a PC
because they have done it a few times is irresponsible at the very least.

It's just as safe as compressed air IMO. If you don't know enough to
avoid static you shouldn't be inside your computer with anything - you
shouldn't even have the side off.

 

[Pete M Williams]

True. Some places are even damper.

Way too much information there for my liking.

I don't want to know about your personal hygiene habits.

Try remarks like that in alt.personal.incontinence and not this newsgroup
please.

If you don't know enough to avoid static you shouldn't be inside your
computer with anything - you shouldn't even have the side off.

I know that, you seem to know that but other people that may read this group
may not.
Hence my warning.

 

[Mercury]

GSV.

The others are indisputably right. I won't use air cans either.

DO NOT use a vacumm cleaner in a computer EVER!

If you want to live on luck that is your business.