Advice on CPU fan weight - A7N8X-E

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K

KWW

I was getting ready to put a really good fan on my son's A7N8X-E, a
Thermaltake Silent Boost A1889-01. I had tried it on another board and, vs
the stock AMD cooling fan (Retail box) it cut about 20C off the temperature
(OK, I also used Arctic Silver with it... vs the stupid tape on the stock
fan...).

The fins are all copper... runs quietly... Anyway, the bummer is, on the
A7N8X I see that there are holes to fasten down the CPU cooling fans that
some with some of the heat sinks I looked at. Also, it doesn't look like
the 462 CPU socket is fastened down to the mobo in any extra special way...
so I wonder if this heatsink is going to be too heavy over the long haul...
what with vibration and all. I like the way it is quiet, and the heat
transfer characteristics of the all copper heat sink are attractive.

Anybody have thoughts/experience/suggestions? I would prefer a fan that did
now howl. I also want to keep the chip cool! If the case were sitting on
its side so that CPU would be flat, that would be one thing, but this case,
as with most of them these days, sits upright.

I do not plan to overclock the system.

TIA!
--
KWW


ASUS A7N8X-E Rev. 1.01
AMD XP+ 2600 (333 FSB)
512 Megs DDR 3200 (yeah... it cost about the same at the time, why not?)
Chaintech GeForce FX5200 DDR 256MB (128 bit datapath)
120 Gb WD EIDE ATA 133
Sony CR/RW
Antec case (either will Run an Antec 300W P/S or a 420W Turbolink CWT 420
P/S)
 
It is true that copper will rip the heat out of the cpu in a hurry but the
sad fact remains as to how you get the heat out of the copper because copper
is a bugger to cool.
Aluminium still can`t be beat as far as that goes.
You will have to do your homework with the weight factor too. I understand
you have a hell of a job booting a computer when the cpu socket and cooler
are laying at the bottom of your case.
 
"KWW" said:
I was getting ready to put a really good fan on my son's A7N8X-E, a
Thermaltake Silent Boost A1889-01. I had tried it on another board and, vs
the stock AMD cooling fan (Retail box) it cut about 20C off the temperature
(OK, I also used Arctic Silver with it... vs the stupid tape on the stock
fan...).

The fins are all copper... runs quietly... Anyway, the bummer is, on the
A7N8X I see that there are holes to fasten down the CPU cooling fans that
some with some of the heat sinks I looked at. Also, it doesn't look like
the 462 CPU socket is fastened down to the mobo in any extra special way...
so I wonder if this heatsink is going to be too heavy over the long haul...
what with vibration and all. I like the way it is quiet, and the heat
transfer characteristics of the all copper heat sink are attractive.

Anybody have thoughts/experience/suggestions? I would prefer a fan that did
now howl. I also want to keep the chip cool! If the case were sitting on
its side so that CPU would be flat, that would be one thing, but this case,
as with most of them these days, sits upright.

I do not plan to overclock the system.

TIA!
Click to expand...

On the Zalman web page for the 7000a, it says:

"Specified maximum weight for a cooler is 450g for the Intel
Pentium 4 and the AMD Athlon 64, and 300g for the AMD
Socket 462 CPU. Special care should be taken when moving a
    computer equipped with a cooler exceeding the weight guideline."

People do use heatsinks which weight more than those limits, but
obviously care must be taken when moving or bumping the equipment.

There is also a spec (somewhere) for how much normal force can
be safely applied to the socket or to the top of the processor
chip (whether it has a heat spreader or not). The normal force
is the force into the board, applied by the clamping mechanism,
and the Intel retail solution must have taken first prize for
applying the most force. The normal force maintains contact
between the heatsink and the processor, under shock and vibration.
Generally, as a user, you don't have a say in that parameter.

As for how to shop for a heatsink - you can have a light/noisy/hot
solution, or a heavy/quiet/cool solution. Heatsinks which use the
screw holes aren't very popular, because the manufacturers got
the impression that people didn't want to remove the motherboard,
to remove the heatsink. For a person constantly pulling the processor,
to try different ones, I guess you could see that point.

Swifttech (swiftnets.com) used to have some heatsinks that used bolts
to hold them down. There was a claim, that a computer equipped with
a bolted heatsink was dropped from a second story window, and on
landing, the heatsink was still in place (although the rest of
the computer case was destroyed). So, using the bolts is definitely
a worthy concept, it is just the convenience of top side clamps
is more popular.

Bolt on solution, now discontinued I think. Might be worth looking
for, if you want something like this.
http://www.swiftnets.com/products/MCX462+ INSTRUCTIONS.pdf

This one uses the socket tabs.
http://www.swiftnets.com/products/MCX462-V-installation-guide.pdf

(All of their installation guides)
http://www.swiftnets.com/installation.htm

The downside of the Swifttech pin fin concept, is when you
use "roughening" as a method of increasing the surface area
of the heatsink, you pay a price in terms of noise. The turbulence
and arrestance of the air path increases cooling efficiency and
noise at the same time.

A second concept, is the Zalman 7000 (either the AlCu or the
pure copper one). It uses sheer size, and plenty of fins, to
get a large surface area, with low resistance to air flow.

http://www.zalman.co.kr/eng/product/view.asp?idx=54&code=005009

This uses a lamination of plates, arranged as fins. Where the
plates clamp together, forms a chunk of metal for the core. A
fan, without noisy housing, provides the cooling air. Thermal
resistance is around 0.22C/W, which is pretty good. It can be
run at full speed without being audible. The downside of this
solution, is its size. As I said above, this one is in the
heavy/quiet/cool camp. Even the AlCu model is still over the
allowed weight for a heatsink, but as long as you uninstall
it before moving the computer, all will be well. If your computer
was going to be a LAN party machine, stick with a bolt-on style
solution, for peace of mind.

Another issue, is the sheer physical dimensions of the thing.
It has a radius of 55mm, measured from the center of the die.
The PSU cannot be butted against the edge of your motherboard,
if using one of these. To figure out the clearance required,
drag a picture of your motherboard into Photoshop. The array
of pins has outer dimensions of 1.8 inches, leaving 0.05 inches
between rows. You can use those dimensions to estimate where
55mm or 2.17" radius can reach. (2.17 - 0.9 = 1.27 inches, from
the last row of pins, to the PSU.) The arrangement of PSU and
motherboard must be such, that a small gap exists between them.
I estimate about 0.35" minimum or so on your board.

The Thermaltake has a thermal resistance of 0.5C/W. This means,
if the processor dissipates 60W, the processor die will be 30C
above the case air temperature. If that was 25C, then the
die will be at 55C or so. The Thermaltake also doesn't have
a weight specified, and is an all copper product.

(You should take some of these thermal resistance ratings or
graphs with a grain of salt, because some I have seen in print,
are just ridiculously good.)

HTH,
Paul
 
Use one on my XP2800.............................
No problems at all.
Motherboard is a A7N8X dlx.
 
On the Zalman web page for the 7000a, it says:
Click to expand...

I've got one of the Zalman 7000AlCu on an Asus A7v. It is a very
quiet heatsink in the low speed mode, yet cools more than the factory
heatsink with its noisy fan.
"Specified maximum weight for a cooler is 450g for the Intel
Pentium 4 and the AMD Athlon 64, and 300g for the AMD
Socket 462 CPU. Special care should be taken when moving a
    computer equipped with a cooler exceeding the weight guideline."
Click to expand...

Not only is there a weight problem, but the Zalman mounting
arrangements are pretty grotty. The four holes around the CPU on my
A7V are almost the same size as the cardboard washers they give you to
put on both sides of the hole. The screws and washers almost pull
through the board. They really should include some shouldered plastic
washers that are of the right size for the motherboard holes.

I've noticed is that Asus didn't do such a good job of selecting an
appropriate CPU thermal sensor on my A7V. It clearly doesn't match
the calibration curves in the associated IC that is reporting the
temperature. The CPU temperature (even within seconds of being turned
on after a long cool-down) shows "40 C" in the bios. The temperature
after hard running for 10 minutes shows "54 C". As best as I can
determine with my dandy Fluke temperature probe is that "54 C
Asus-thermal-units" corresponds to around 40-degrees Celsius.
Touching the heatsink hear the base confirms that it feels roughly
"body temperature".

I was very concerned about the possibility of the heatsink not having
been making good contact. Pulling off the heatsink showed that the
heatsink paste had been squeezed uniformly. It wasn't a case of the
heatsink not seating deeply enough with insufficient pressure. I was
still worried about the possibility of a trapped air bubble so I wiped
off the grease and re-applied it a second time and tested again. The
results were the same.

I'm now leaning towards the conclusion that one can't trust the
calibration of the ASUS. One needs to use a real temperature probe to
convert from Asus temperature units to degrees C or F. Folks that
think they are running hot should at least make sure that the heatsink
really feels hot near the base.

<include standard disclaimer for not sticking body parts into rotating
cooling elements>

-wolfgang
 
I was getting ready to put a really good fan on my son's A7N8X-E, a
Thermaltake Silent Boost A1889-01. I had tried it on another board and, vs
the stock AMD cooling fan (Retail box) it cut about 20C off the temperature
(OK, I also used Arctic Silver with it... vs the stupid tape on the stock
fan...).

The fins are all copper... runs quietly... Anyway, the bummer is, on the
A7N8X I see that there are holes to fasten down the CPU cooling fans that
some with some of the heat sinks I looked at. Also, it doesn't look like
the 462 CPU socket is fastened down to the mobo in any extra special way...
so I wonder if this heatsink is going to be too heavy over the long haul...
what with vibration and all. I like the way it is quiet, and the heat
transfer characteristics of the all copper heat sink are attractive.
Click to expand...

I hope there isn't any problem with it, because I put that
very same cooler on my A7N8X-E Dlx a week ago. :-)

Kind regards.
 
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