A8N-SLI Premium -- reported temps

[GSV Three Minds in a Can]

Yup, that's why the A8N-SLI Premium's heatpipe cooling works in the
horizontal position as well as vertical and why some CPU heatpipe
coolers claim to work equally well regardless of the position in which
they're installed.
I think the heatpipe cooling on the A8N-SLI Premium is working
superbly for almost all users. I have read posts, however, of
chipsets that are too hot to touch, even when the board is mounted as
intended. It's starting to sound as though there may be some
manufacturing defects, but I've not read that this has been confirmed,
yet. It would take someone RMAing their hot board and then getting a
cool chipset on their replacement to be sure. So far, I just haven't
noted anyone reporting that. At this point, all we know is that there
is great disparity in the chipset temps from board to board, ranging
from "cool to the touch" to "too hot to touch." The differences are
so great, that it's difficult for me to believe that they could be
accounted for by variations in enclosures, other components installed,
or heatsink ventilation.

Over (or under) filling the heatpipe with working fluid will have a
catastrophic effect on its performance - I'd suspect that as a failure
mode if someone is seeing a really hot chipset, and an apparently not
working heatpipe.

 

[RJT]

The fluid actually =boils=, soaking up latent heat
of vaporisation, and the vapour condenses (releasing the same latent
heat) at the cold end, and then runs back (or is wicked back) to the hot
end.

True, the heat is taken into the fluid by vaporisation, and released by
condensation. That's how the energy gets taken into and released from
the pipe. But the pipe has to do something else too: transport it. The
vapour has to go to the cold end, and the fluid to the hot end. Hot
vapour tends to rise. So I don't see how an upside down heatpipe will
get the hot vapour to go DOWN and the cold liquid to go UP. There might
be some small flow out of pressure differences in the pipe, but I doubt
it will work as efficient as it will when the heat is taken up in the
lowest part and released at the top.

 

[GSV Three Minds in a Can]

True, the heat is taken into the fluid by vaporisation, and released by
condensation. That's how the energy gets taken into and released from
the pipe. But the pipe has to do something else too: transport it. The
vapour has to go to the cold end, and the fluid to the hot end. Hot
vapour tends to rise. So I don't see how an upside down heatpipe will
get the hot vapour to go DOWN and the cold liquid to go UP. There might
be some small flow out of pressure differences in the pipe, but I doubt
it will work as efficient as it will when the heat is taken up in the
lowest part and released at the top.

The vapour will condense at the cold end, where-ever that happens to be
(up, down, sideways, not interesting really). Yes, to get the liquid to
run back to the hot end you can use gravity, in which case it helps if
the hot end is 'down', however most heat pipes for PC cooling use have a
wick, which is capable of getting liquids uphill (certainly a few
inches).

The main purpose of the 'pipe' is to =contain= the liquid/vapour, rather
than transport it.

 

[milleron]

The vapour will condense at the cold end, where-ever that happens to be
(up, down, sideways, not interesting really). Yes, to get the liquid to
run back to the hot end you can use gravity, in which case it helps if
the hot end is 'down', however most heat pipes for PC cooling use have a
wick, which is capable of getting liquids uphill (certainly a few
inches).

The main purpose of the 'pipe' is to =contain= the liquid/vapour, rather
than transport it.

All true, and very good implementations of these techniques can work
against gravity, but the A8N-SLI Premium does NOT. I suppose it's
possible that they left out the wick. I'm thinking that with the
system mounted correctly, the condensate might get back to the chipset
faster withOUT the wick, so perhaps that's what they did.

Look for this problem to be corrected in the A8N-SLI Ultra-Premium
Elite. For now though, barring manufacturing defects, let me tell ya
that this system works marvelously well if it's mounted as the
designers intended.

Ron

 

[kenn]

True, the heat is taken into the fluid by vaporisation, and
released by
condensation. That's how the energy gets taken into and
released from
the pipe. But the pipe has to do something else too: transport
it. The
vapour has to go to the cold end, and the fluid to the hot
end. Hot
vapour tends to rise. So I don't see how an upside down
heatpipe will
get the hot vapour to go DOWN and the cold liquid to go UP.
There might
be some small flow out of pressure differences in the pipe,
but I doubt
it will work as efficient as it will when the heat is taken up
in the
lowest part and released at the top.

I’m gonna have to second that. In fact, i think it’ll work even worse
than air cooling because all the heated air is "trapped" at the top
end of the pipe. Due to the pressure gradient (the heated ones being
the low pressure), the only way the heat can escape, will be like an
uphill battle, pushing its way down to the heat sink where the
pressure is higher.

It’s like a classic case of working against nature.

For those who got this inverted setup working, i believe, you would be
getting an even better result if you have it the other way around.

From what i’m seeing, the only is to replace the pipe with h20 or the
g’old air.

Kenneth

 

[RJT]

The vapour will condense at the cold end, where-ever that happens to be
(up, down, sideways, not interesting really). Yes, to get the liquid to
run back to the hot end you can use gravity, in which case it helps if
the hot end is 'down', however most heat pipes for PC cooling use have a
wick, which is capable of getting liquids uphill (certainly a few inches).

The main purpose of the 'pipe' is to =contain= the liquid/vapour, rather
than transport it.

Not true. The main purpose of any heatpipe is to move the heat. A
heatpipe without a heatsink is like installing watercooling without a
radiator - pointless.

Heatpipes can be built with a wick structure to support a certain flow,
but pipes that effectively transport the heat downward - and thus the
cool liquid upward - need a wick structure fine enough to create a
capillary effect for the liquid to move upward (rather than gravity
pulling it down). This can work, but will definately make the pipe less
effective, as the capillary effect can only be assured through making
the tube inside thin - and thus less free flow is possible.

Any heatpipe will work best when the heat is transported upwards to cool
down at the top. Do a bit of googling. Even at the Thermalright website
they acknowledge that gravity effects the pipes. They use multiple
pipes, so there's always one that oriented right way up for maximum effect.

I found a review on heatpipe cooling, so here's a little snip from that:

Orientation plays a big role in how well a heat pipe will work. Gravity
is required to make it operate properly. With the Tower112 Thermaltake
made one rather large mistake in the design. While this cooler works
fantastic while upright (desktop orientation) it does not work so well
in a standard tower case. You will find that this is the case with most
heat pipe solutions. I did not test the unit in the horizontal
orientation of a tower case so I can't comment on if the temperatures
would differ, but I know from the research that I did on heat pipes for
this article that orientation plays a key role in the effectiveness.
(http://www.thecrucible.ca/reviews/tower112/index.htm)

Just a few links Google turned up:

http://www.tsheatronics.co.jp/english/technology/
http://www.teschke.de/heatpipes/News/informations/General_infos/general_infos.html

 

[GSV Three Minds in a Can]

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

Not true.

Which bit do you believe to be not true? I can't work it out from your
comments.

The main purpose of any heatpipe is to move the heat. A heatpipe
without a heatsink is like installing watercooling without a radiator -
pointless.

True, but I didn't say anything about the HS on the other end of the
pipe.

Heatpipes can be built with a wick structure to support a certain flow,
but pipes that effectively transport the heat downward - and thus the
cool liquid upward - need a wick structure fine enough to create a
capillary effect for the liquid to move upward (rather than gravity
pulling it down). This can work, but will definately make the pipe less
effective, as the capillary effect can only be assured through making
the tube inside thin - and thus less free flow is possible.

No, you just need to make the wick =structure= fine. This is independent
of the diameter of the tube that contains it.

Any heatpipe will work best when the heat is transported upwards to
cool down at the top. Do a bit of googling. Even at the Thermalright
website they acknowledge that gravity effects the pipes. They use
multiple pipes, so there's always one that oriented right way up for
maximum effect.

I don't dispute they work =better= with gravity assisting the return
flow of liquid. What I did dispute is that they =only= (or =can only=)
work with the cold end at the top. T'aint true, they can (if properly
designed & constructed) work in any orientation.

 

[GSV Three Minds in a Can]

Bitstring

I’m gonna have to second that. In fact, i think it’ll work even worse
than air cooling because all the heated air is "trapped" at the top
end of the pipe.

Air - what air? The pipe is filled with (or should be) working fluid
plus vapour of working fluid. Ain't no stinking air!

Due to the pressure gradient (the heated ones being
the low pressure), the only way the heat can escape, will be like an
uphill battle, pushing its way down to the heat sink where the
pressure is higher.

At the heatsink end the vapour condenses into liquid. The pressure is
thus way lower, so more vapour rushes in.

Look, hook your kettle spout up to your freezer .. all the heat
generated by boiling the water =will= wind up in the freezer (along with
all the water that was in the kettle) whether the freezer was up, down,
or sideways.. The only trick with a heatpipe is that you need to get the
water back into the kettle (continuously) .. and picking a better
working fluid than water.

 

[RJT]

Bitstring <[email protected]>, from the wonderful person RJT

Lemme recap. You said:

I said:

You said:

True, but I didn't say anything about the HS on the other end of the pipe.

So which is it? Is the main purpose to =contain= or to =move=? You
didn't mention a heatsink because you said the main purpose is to
=contain= the liquid/vapour, rather than transport it. Stricktly, the
pipe needs to contain the liquid, where the liquid needs to =move= to
transport the heat. So the heatpipe as a whole is designed to =move=
heat, not contain it.

you just need to make the wick =structure= fine. This is independent
of the diameter of the tube that contains it.

Capillary effect - look it up.

You then said:

I don't dispute they work =better= with gravity assisting the return
flow of liquid.

Hmmm. Lemme read this back:

I said:

A heatpipe works like this: the fluid inside gets hot, the rises up
to the top to cool down, then descends again to be re-heated, thus
creating a flow inside the pipe.

You said:

Close but no cigar. The fluid actually =boils=, soaking up latent
heat of vaporisation, and the vapour condenses (releasing the same
latent heat) at the cold end, and then runs back (or is wicked
back) to the hot end.

The point is: it doesnt just run back. You make it seem like =any=
heatpipe will work upside down just fine, due to their nature. Sorry,
but that just isn't true. In fact, most won't, as most aren't designed
to work upside down. The last bit you said is more like it:

I don't dispute they work =better= with gravity assisting the return
flow of liquid. What I did dispute is that they =only= (or =can only=)
work with the cold end at the top. T'aint true, they can (if properly
designed & constructed) work in any orientation.

You also said:

The only trick with a heatpipe is that you
need to get the water back into the kettle (continuously)

Exactly.
Not all will =only= work right way up, but most will. Most aren't
properly designed to work in any orientation. They don't have that 'trick'.

So, to get back to the original post: someone with an ASUS Premium
heatpipe board was having way too high temps when he placed the board
upside down. My point was the heatpipe (left out the word 'probably')
wasn't designed to work upside down, like most heatpipes are. Your post
'Close but no cigar' made it look like that assumption was wrong, and
that =all= heatpipes work regardless of their orientation.

I know I'm right. 'nuf said.

RJT

 

[GSV Three Minds in a Can]

Lemme recap. You said:

Note the LIQUID/VAPOUR .. not HEAT, Liquid/Vapour. And note I'm talking
about the pipe, i.e. the metal bit you can see that looks like a pipe,
not the whole thing, which (hopefully) has a wick, and some working
fluid in it.

I said:


You said:


So which is it? Is the main purpose to =contain=

As I said the purpose is to CONTAIN the liquid/vapour. The purpose of
the liquid/vapour is to move the heat. That's why it's called a heat
pipe, it moves heat .. the pipe itself doesn't have to move any liquid -
the capillary wick inside the heat pipe has to. If they left out the
wick, they built a damn stupid heat pipe.

or to =move=? You didn't mention a heatsink because you said the main
purpose is to =contain= the liquid/vapour, rather than transport it.
Stricktly, the pipe needs to contain the liquid, where the liquid needs
to =move= to transport the heat. So the heatpipe as a whole is designed
=move= heat, not contain it.


Capillary effect - look it up.

I have a Masters degree in science, I don't need to. You can get nice
capillary lift inside a 200ft diameter pipe, if you use the right wick
material.

I know I'm right. 'nuf said.

Oh well, in that case I'll just go hang myself then ... Oh wait wasn't
it you that said

A heatpipe works like this: the fluid inside gets hot, the rises up to
the top to cool down, then descends again to be re-heated, thus
creating a flow inside the pipe.

Excuse me, the =fluid= does =NOT= rise. Vapour rises - or actually
'travels' - to wherever the cold end happens to be. And yes, then the
fluid that it condenses to has to be sent back (which may, but does not
have to be, 'descending'). But that's where we came in.

 

[kenn]

Bitstring
from the


Air - what air? The pipe is filled with (or should be) working
fluid
plus vapour of working fluid. Ain't no stinking air!


At the heatsink end the vapour condenses into liquid. The
pressure is
thus way lower, so more vapour rushes in.

Look, hook your kettle spout up to your freezer .. all the
heat
generated by boiling the water =will= wind up in the freezer
(along with
all the water that was in the kettle) whether the freezer was
up, down,
or sideways.. The only trick with a heatpipe is that you need
to get the
water back into the kettle (continuously) .. and picking a
better
working fluid than water.

OK, so it’s vapor, instead of heated air. The general conclusion is
still the same - the fluid is on the wrong end of the pipe. It just
won’t work. But one thing for sure - the pipe can’t be all filled with
fluid, otherwise, how would there be room for vapor.

Just that it’s such a waste that i have to replace this with a water
block. After all it’s one of the "feature enhancement" over the
deluxe version that they boost on every review.

Kenneth

 

[GSV Three Minds in a Can]

Bitstring
<[email protected]>, from the

OK, so it’s vapor, instead of heated air. The general conclusion is
still the same - the fluid is on the wrong end of the pipe. It just
won’t work. But one thing for sure - the pipe can’t be all filled with
fluid, otherwise, how would there be room for vapor.

Yep, the amount of fluid (liquid) in the system is critical - too much
or too little and it won't work properly.

Just that it’s such a waste that i have to replace this with a water
block. After all it’s one of the "feature enhancement" over the
deluxe version that they boost on every review.

I'm quite prepared to believe that ASUS have (once again) delivered a
marketing gimmick instead or proper engineering. Much as I love them,
the 40mm chipset fan (e.g. on the A7V133s) was a joke, more so since the
HS part was stuck to the (concave!) top of the chip package with double
sided sticky tape or similar.

Not sure I'd bother with water cooling though - people seem to manage
just fine with a (proper, properly attached) passive HS.

 

[RJT]

Excuse me, the =fluid= does =NOT= rise. Vapour rises - or actually
'travels' - to wherever the cold end happens to be. And yes, then the
fluid that it condenses to has to be sent back (which may, but does not
have to be, 'descending').

Vapour - in a closed pipe filled with fluid.

Oh, and if there is room for vapour - guess what happens if I heat only
the top bit.

Good luck with that Masters.

RJT.

 

[GSV Three Minds in a Can]

Vapour - in a closed pipe filled with fluid.

It isn't "filled". I don't believe anyone on this thread was stupid
enough to assume 'filled' .. oh, except you. 8>.

Oh, and if there is room for vapour - guess what happens if I heat only
the top bit.

Your heatpipe doesn't work unless the condensed working fluid can get
(back) to the hot end (or close enough to be vaporised), and the vapour
can get to the cool end (or close enough to condense). That's where
wicks &/or gravity come in.

Good luck with that Masters.

Don't need luck, got the piece of paper. Had it a long time too ..
probably longer than you've been alive.

One last time - a proper heat pipe requires PHASE CHANGE from liquid to
vapour and back. They do not work by convection or conduction in a tube
'filled' with liquid. Nor does a solid lump of copper bar count.

 

[milleron]

Bitstring
<[email protected]>, from the


Yep, the amount of fluid (liquid) in the system is critical - too much
or too little and it won't work properly.


I'm quite prepared to believe that ASUS have (once again) delivered a
marketing gimmick instead or proper engineering.

Nah, the heatpipe cooling on the A8N-SLI Premium is engineered
perfectly and works perfectly for the VAST majority of owners. It
looks a lot more likely that there are simply some manufacturing
defects out there. All boards, no matter how well engineered, have a
few DOAs simply because errors in manufacturing are inevitable on some
scale.

snip

Ron

 

[RJT]

Your heatpipe doesn't work unless the condensed working fluid can get
(back) to the hot end (or close enough to be vaporised), and the vapour
can get to the cool end (or close enough to condense). That's where
wicks &/or gravity come in.

Gravity on vapour vs gravity on liquid, in an upsidedown heatpipe. Cool.
I'll stick with my advice:

RJT, 35, LL.M.

 

[GSV Three Minds in a Can]

Gravity on vapour vs gravity on liquid, in an upsidedown heatpipe. Cool.
I'll stick with my advice:

You appear to have selective blindness w.r.t. all my comments about
wicking. Wicks moves liquids uphill. Heatpipes typically have wicks ..
those that don't won't function upside down, sideways, or in zero
gravity.

RJT, 35, LL.M.

GSV, MA [cantab] Nat Sci, MBCS, C.Eng (retired).

 

[GSV Three Minds in a Can]

If anyone is still struggling with the fundamentals of heatpipes (and
can pass a basic comprehension test), there is a useful, simple, and
only 6 years out of date, explanation at:

http://www.electronics-cooling.com/html/1999_may_article2.html

That one used water - very good from a latent heat perspective, pretty
sucky from handling difficulties, like needing very low pressure in the
pipe if you want it boiling at the sort of temperatures we'd want a chip
kept at.

The referenced Peterson book is reported to be great if you want to
design your own HP, but I believe it's a trifle on the expensive side at
over $100.