Re: FX 60 HSF and Case Recommendation
- From: nospam@xxxxxxxxxx (Paul)
- Date: Sun, 18 Jun 2006 04:05:06 -0400
In article <FD1lg.2227$RU4.1860@trnddc03>, "unlabeled" <nospam@xxxxxxxxxx>
wrote:
I have a client who is a heavy game player and is having problems with 65c+
cpu temps.
She's running:
FX 60 (stock hsf)
A8N32-SLI Deluxe
2 GB generic ram
Dual Nvidia 7800s
650W PSU (I forget the manufacturer, but it's a good one)
2 PATA HDDs (20GB and 250GB both Maxtors)
Antec minitower (front and back 120 fans and one side 90 fan)
Water cooling is not an option, I need a good air cooled case and HSF
recommendation.
I should add she lives in an old apartment whose wiring will not support an
air conditioner, so the room temps are high.
TIA,
john
If your customer is running a system like that, in summer, she'll
incinerate. It is all too easy for a high power gaming system to
lift the room temperature, and most people would rapidly lose
interest in gaming if the room temperature shoots up. (This is
a problem in my computer room - I only run AC at night, as the two
speed fan on my AC is busted, and only works right at low speed.)
For the computer case itself,
CFM = 3.16 x Watts / (allowed temp rise deg F)
FX60 is 120 Watts when Vcore efficiency is taken into account.
(110W / 0.90).
A 7800GT is close to 60W.
http://www.xbitlabs.com/articles/video/display/gpu-consumption2006_5.html
The total for the major components is 240W. If we set the case temp
rise to 10F (well cooled), that gives CFM = 3.16 * 240 / 10 = 76CFM.
Your average 80mm fan might be 35CFM ot so, so this would be two
average 80mm fans mounted one above the other, exhausting out the
back of the computer. Or maybe a good 120mm. The other part of the
equation, is making sure there is enough vent space for a fan like
that to do its job. It cannot exhaust the needed 76CFM, without
a vent hole big enough for that amount of airflow.
If you want a good 120mm, try one of these (121 CFM). I got one of
these at a local electronics store, and I run it at reduced voltage.
It is "too much of a good thing" when fed a full 12V. Note that, due
to the 1A power consumption, special care should be used feeding it.
You can wire it to the 12V and GND on a disk drive Molex, for the
full 12V, or wire red and black to 12V and 5V respectively, to get
a 7V feed. The fan has no tacho wire, so using the 12V and 5V wire
trick won't upset the tacho signal. (For the 12V and 5V wire trick
to work properly, there has to be enough load on +5V, so that you
don't cause the +5V voltage to shoot up. As long as there are a
couple disk drives as electrical loads, you should be OK.)
Otherwise, you'll need a rheobus with a 1A rating, to reduce the
voltage coming from a Molex disk drive connector. I would not
connect this fan to a motherboard header.
http://www.circuittest.com/English/Content/Items/CFA1212038MS.asp
One trick to bringing the case temp down, is ducting hot devices
so that their exhaust air cannot recirculate within the case. It
is pretty hard to do that for the processor, as you should have a
bit of cooling air available for the Vcore regulation circuitry
(MOSFETs).
Some cases use zoning (place dividers within the case), to separate
the hot devices, and provide a separate cooling path. Cases like that
tend to be larger, and the case holds less stuff when it has zoning.
So, lets try some other numbers. If the room temp is 25C, the well
cooled computer case air temp is 32C (i.e. 10F or 7C higher than
room temp), and our 110W processor is sitting at 65C, what is the
theta_R of the heatsink ? (65C - 32C)/110W = 0.3C/W . In this case,
the power dissipation is just the processor component and doesn't
include the Vcore circuit, and that is why 110W is used. The 0.3C/W
number might represent a typical cheap heatsink. The theta_R
number can be as low as 0.12C/W, and if we work the numbers with that,
we get 110W * 0.12C/W = 13.2C . In other words, if we had this
magically good heatsink, the CPU would only be 13.2C hotter than
the computer case air. If you only managed to cool the computer case
to 40C, then the CPU would be 53.2C .
So you have two "levers" to work with. You can either inprove the
case cooling, to bring the computer case delta down to the 7C
figure. Or you can put in a whacking great after market CPU
heatsink. Or both.
A CNPS9500 LED running from 12V, will give a theta_R of 0.12C/W .
http://www.zalman.co.kr/eng/product/view.asp?idx=165&code=005
An Ultra-120 is another candidate - fan purchase is separate.
http://www.thermalright.com/a_page/main_product_ultra120.htm
http://www.overclockers.com/articles1329/ (0.12C/W is possible)
The Ultra-90 is a bit smaller and 0.14 - 0.16C/W depending on fan:
http://www.overclockers.com/articles1314/
With the Ultras, you might be able to cook up an exhaust duct
that pointed at one of the rear fans. All of these CPU coolers
are quite large, and the major challenge is figuring out whether
they will fit, before you buy them.
Now, one concern would be, that the AMD stock heatsink already
has heatpipes on it, and isn't supposed to be that bad a
heatsink. A good heatsink should have shipped with the FX-60,
and I really wonder whether an aftermarket heatsink is going
to make a big difference. One site (madshrimps) tested the
stock AMD heatpipe based heatsink, and found it was 1C cooler
than an XP-90. And an XP-90 is about 0.16C/W with a low speed
fan...
An NV Silencer can be used to vent video card exhaust
straight out of the case. Assuming the stock cooler isn't
already doing that.
http://www.arctic-cooling.com/vga2.php?idx=40
I think I'd only change the computer case, if I ran
out of other things to try. I hope your customer has
an unlimited budget :-)
"COOLER MASTER CM Stacker"
http://www.newegg.com/Product/Product.asp?Item=N82E16811119042
More description here:
http://www.zipzoomfly.com/jsp/ProductDetail.jsp?ProductCode=141623
This optional accessory blows air aross the plane of the
motherboard.
http://www.zipzoomfly.com/jsp/ProductDetail.jsp?ProductCode=370696
The 4-in-3 module houses a 120mm fan and some hard drives and sits
in the front bay area.
http://www.coolermaster.com/index.php?LT=english&Language_s=2&url_place=product&p_serial=STB-3T4-E1&other_title=4
There are probably a ton of other cases that are as nice.
This is an example of zoned cooling. A disadvantage of this
case, is I think it installs the motherboard upside-down (180
degree rotation from the normal position), and that is a problem
with any motherboard that uses heatpipe chipset coolers. So I
would not fit an A8N32 into one of these. I believe there are
some Lian-Li cases that mount the boards upside-down as well.
http://www.silverstonetek.com/products/tj06/interior/tj06.jpg
So keep looking and you are bound to find something appropriate.
Like I tell so many people working on stuff like this, you need
to measure: room temp, computer case air temp, CPU temp, all while
a 100% load is applied to the CPU - in this case two copies of
Prime95 or some other mechanism to load up both cores. That test
will allow you to collect data useful for analysing what needs to be
changed. If the computer case is causing the problem (delta is more
than 7C/10F), and not the CPU fan, then start with a better
120mm exhaust fan, and work from there. The NV Silencers would be
added second (to cut down on video card contribution to computer
case heating). Next, the CPU heatsink, to try to get a better
theta_R. And finally, a completely new case.
Note as well, in terms of the "room heating" issue, there are some
(more expensive) power supplies that feature "80+ percent efficiency".
Those kinds of power supplies, mean that less waste heat is
created by the power supply. It is a relatively expensive way to
remove 25-50W of room heating. If the customer wants every possible
improvement, that is yet another mod to consider. That won't help
with the CPU temperature, but it will make a minor improvement
to the room heating problem.
If she would agree to water cooling, you could mount the radiator
out on a window sill :-)
Paul
.
- References:
- FX 60 HSF and Case Recommendation
- From: unlabeled
- FX 60 HSF and Case Recommendation
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