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Haven't Built a Machine in Years...Cooling Concerns

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May 26, 2012 4:54:42 PM

Hello All,
I haven't build my own PC in years so I'm a bit out of the loop. I've been looking around and many vendors and I can't seem to find the build I want -- from a vendor with reliably -- so I'd like to build my own box.

That being said, I have no problems building a machine but I am concerned about issues like fans, thermal paste, heat sinks, cooling and the like. I'm not interested in liquid cooling, but I do want to build a machine that won't melt down. I'm thinking in the core i5 or core i7 range for the CPU and it will be a workstation type machine, with no gaming.

I know there are tutorials out there and I've looked -- but I couldn't seem to get the answers to these questions specifically.

I. Just to clarify -- is this the order of "stacking"?

A. CPU
B. thermal paste
C. heat sink
D. fan

2. Are the stock components that come with the chips adequate? Do I need "special" thermal paste or a "special" heat sink?

3. And is this enough to keep the computer cool (I'm going to go with a mini-tower with a few 3.5" expansion bays) along with the fans that come with a tower case?

Thank you so much in advance for any advice!
R

a c 135 à CPUs
May 26, 2012 5:03:22 PM

1. I have a hard time imagining how someone could think of 'stacking' in any other order except as a joke
2. stock HSF is adequate for stock-clock operation in a case with decent airflow when properly installed at least for the first 2-3 years. Beyond that, you may need to start looking at aftermarket HSF since the plastic push-pins and frame will deform over time and reduce the contact pressure on the CPU
3. depends on how many fans come with the case, how good they are, their placement and obstacles that may divert airflow away from where it needs to go to be effective
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May 26, 2012 5:07:34 PM

InvalidError said:
1. I have a hard time imagining how someone could think of 'stacking' in any other order except as a joke
2. stock HSF is adequate for stock-clock operation in a case with decent airflow when properly installed at least for the first 2-3 years. Beyond that, you may need to start looking at aftermarket HSF since the plastic push-pins and frame will deform over time and reduce the contact pressure on the CPU
3. depends on how many fans come with the case, how good they are, their placement and obstacles that may divert airflow away from where it needs to go to be effective


Thank you for your reply.

Can you recommend:

a) a thermal paste/heat sink/fan combination that is aftermarket that would not require going back to be replaced?

b) a case that will support 3-4 3.5" external bays that comes already with good air flow and fans already built in?

Thanks.

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a c 135 à CPUs
May 26, 2012 5:41:44 PM

a) CM Hyper 212+ / 212 EVO are the highest performance HSF under $50 on the market (212+ is/was on sale at Microcenter for $11) and is a huge improvement over the stock HSF if it fits on your motherboard and inside your case. CM's mystery goo included with 212 +/EVO is almost just as good as any other, coming only 1-2C short of AS5 in reviews which is insignificant unless doing extreme overclocking.

b) most cases only come with top and rear fans, you have to add other fans yourself. Some fancier cases include a front 140mm fan. If you want a relatively inexpensive but mostly well-built no-frills case, the Antec 302 would be worth looking into, just need to add a pair of 120mm front fans.
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a c 80 à CPUs
May 26, 2012 10:19:30 PM

Cooling is the smallest issue its ever been as components are generating less heat, and cases are much better designed (with a few exceptions). Providing you have airflow from front to back and a reasonable HSF (as mentioned above) you'll be fine.

The fractal cases are all good, Antecs are good and there are others.
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a c 196 à CPUs
May 26, 2012 11:06:02 PM

when building a pc it not just heat but buying parts from known good vendors. a lot of people try to price shop first then find out that the ps or mb they bought has a high doe rate or is over rated. as this is going to be a work station i would look at case like the r300. it a gaming case but it has a nice large fan in front as a pull fan. (larger fans will let you run them at slower speeds keeping the sound level of your pc down.) with the cpu look into the low power intel and amd chips. http://ark.intel.com/products/65521/Intel-Core-i5-3570T...
lower it tdp the cooler the chip going to run on air. thermal paste there a few good brands...myself use arctic silver. with cpu cooling with air you can have one large copper or metal brick. or you can do a combo brick with a large fan. the trick is how the vendor rated there heat sink in wattage. ie you would not put a 60w heat sink on a 77w ib chip. it would not be able to keep uo with the heat load.
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a b à CPUs
May 26, 2012 11:30:21 PM

stock heatsink and fan you should expect idle at ~35c, and load of 50-60c, and you do not run into any risky temps until after 90c, so the stock fan is more than adequate for running stock, or even a minor OC bump (though not much).

my own setup with an i7 2600 idles at ~30 (29-31 depending on the core you look at), and then when maxed out with a turbo overclock (it is a locked chip so I cannot do a real OC) of 4.2GHz it hits a max of 51c. This is using a Hyper 212Evo with 2 120mm fans running at 800rpm (similar performance as the stock fan... just quieter) and the stock paste that came with the EVO.

In short; Heat is not the issue for modern builds unless you are OCing, and even then a nice cheap cooler will do wonders for OCing.

For your questions:
1) um yes, thermal paste goes between the CPU and heatsink... where else would you put it?
2) Stock heat sinks and fans are actuially overkill for your CPU, unless you are overclocking. If you are overclocking on a consumer (sandybridge or Ivybridge) CPU then a $30 or less cooler will be more than adequate. If you are getting a bigger CPU (Sandy Bridge E, or Xeon) then a $30cpu is needed for stock speeds (as they do not come with fans), and a $75+ cooler is suggested for overclocking.

Beware of over-sized heatsinks! The Hyper 212+/EVO (and many similar heatsinks) are very tall and require a fair amount of clearance in your case to fit. You cannot cut these coolers down as they have heat pipes which contain water. If you loose the water, then they simply do not work well. Some other heat sinks can interfere with the height of some ram sticks, but this is generally less of a problem unless getting an extremely large cooler.

3) Keeping the whole computer cool has more to do with the airflow of the case, not just the CPU cooler. I always recommend having at least one fan in front pulling air in, and one fan in back taking air out. They do not need to be big fans, or very fast, just enough to keep a constant exchange of air, and place it in a spot where it is not going to suck hot exhaust air back into the system.
Having a bottom mounted power supply is a plus as well.
Also, if you live in a hot area, then make sure that the ambient temp of the room does not surpass 80*f, as this is the point where many electronics begin to have issues coping with the heat when under load.


... you can always use the stock cooler, and add an aftermarket cooler later if you need it.
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a c 334 à CPUs
May 26, 2012 11:33:19 PM

Current cpu chips are built on 32 or 22nm processes, and run much cooler than those of even a few years ago.
They also do more work per clock cycle, particularly the Intel sandy bridge and ivy bridge chips.

The box will come with a stock heat sink with fan attached and with pre applied thermal material.
It is entirely adequate. Under load, the fan will spin up, and be a bit noise.
The chips have protective circuitry that will slow the cpu down or even turn it off if there should be some dangerous thermal condition. Not a big worry.

The stock Intel cooler is a bit tricky to install.

To mount the Intel stock cooler properly, place the motherboard on top of the foam or cardboard backing that was packed with it.
The stock cooler will come with paste pre applied, it looks like three grey strips.
The 4 push pins should come in the proper position for installation, that is with the pins rotated in the direction of the arrow,(counter clockwise) as far as they can go.
Place the cooler so that all 4 pins are oriented over the holes in the motherboard.
Push down on the entire cooler so that all 4 pins are through the motherboard.
When you push down on the top black pins, it expands the white plastic pins to fix the cooler in place.

The trick to getting it on is to push down on a diagonal pair of pins at the same time. Then the other pair.
If you do them one at a time, you will not get the cooler on straight.
Lastly, look at the back of the motherboard to verify that all 4 pins are equally through the motherboard, and that the cooler is on firmly.
This last step must be done, which is why the motherboard must be out of the case to do the job.
It is possible to mount the cooler with the motherboard mounted in the case, but you can then never be certain that the push pins are inserted properly.

If you should need to remove the cooler, turn the pins clockwise to unlock them. You will need to clean off the old paste and reapply new if you ever take the cooler off.

Now, all that said, I suggest using an aftermarket cooler like the cm hiper212.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
At $20, it is a very effective cooler. The larger 120mm fan spins slower, so it is not at all noisy under load.
A big advantage for the novice is that it uses a backplate mount which is much simpler.

As to a case, you can start with the Antec 300. The illusion model comes with two extra front 120mm fans. Not really necessary, but nice.
A couple of thousand reviewers can't ve very wrong about liking the case.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

As a suggestion, download and read the case and motherboard manuals. Many questions will be answered.
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a c 135 à CPUs
May 26, 2012 11:59:26 PM

smorizio said:
the trick is how the vendor rated there heat sink in wattage. ie you would not put a 60w heat sink on a 77w ib chip. it would not be able to keep uo with the heat load.

If you look at how small Intel's stock heatsinks are even for 95W chips, I doubt there are many aftermarket HSF "rated" for less than 120-150W.

From an engineering standpoint, heatsinks are not rated by "wattage" since heatsinks can handle any wattage and temperature difference up to however high it needs to go until structural failure and this limit is several times higher than what happens inside a PC... Intel's stock orb heatsink could handle several kW if the application allowed 200C temperature rise. Heatsinks are rated by case-air thermal resistance and how slowly/quickly heat propagates through them... how efficiently and quickly they can move heat from A to B at a given temperature difference and airflow.

Because the average user does not know how to pick HSF based on case-ambient thermal resistance, ambient temperature, airflow, etc., things get dumbed down to a list of CPUs the HSF should suitable for in a typical install and room temperature.
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a c 196 à CPUs
May 28, 2012 2:24:23 AM

inv i thought intel and vendors rated there cooling on the intel thermal profile rated in wattages...that why i thought with a lot of new ib chips came out they still have the 77w that are stamped on the sb chip boxes.
http://download.intel.com/design/processor/designex/322...
looks like one side of the chart on 6.1 shows wattage to case temps.
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a b à CPUs
May 28, 2012 3:49:27 AM

smorizio said:
inv i thought intel and vendors rated there cooling on the intel thermal profile rated in wattages...that why i thought with a lot of new ib chips came out they still have the 77w that are stamped on the sb chip boxes.
http://download.intel.com/design/processor/designex/322...
looks like one side of the chart on 6.1 shows wattage to case temps.

you would be correct. The wattage rating is merely how much energy can be applied to a heatsink in a 72*f room before the heatsink reaches the critical mark for a CPU (~95*c). This tells us how much energy (wattage) can be applied to the CPU before we could expect failures, and all HSF sets are rated (if rated at all) to be on the safe said of failure.
According to Invalid's analogy then CPUs are rated improperly because they can run much hotter before they tend to be unusable. Just because something can do more, does not mean that it was designed to be useful with the heavier load. Things are simply rated based upon how they were designed to be used.
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a c 135 à CPUs
May 28, 2012 4:45:28 AM

smorizio said:
looks like one side of the chart on 6.1 shows wattage to case temps.

Not quite. Table 6.1 tells you TDP in various operating modes and min/max Tcase at various thermal load levels, it means absolutely nothing for heatsink design other than heatsinks need to be able to make this thermal profile happen under whatever environmental circumstances they are intended to be used in. Cooling a 95W CPU in a 1U server located in a 20C temperature-controlled datacenter is going to require a completely different thermal solution than cooling the same CPU in a sealed outdoor enclosure with 60C thermal loading.

If heatsinks were designed for exactly 95W and meet Intel's TTV profile, all heatsinks would cause i7-8xx to hit ~70C case temperature at full load as per table 6.2. In practice, you get case/package temps under 50C which means aftermarket HSF are massively outperforming Intel's TTV requirements under typical desktop operating conditions.

Rating HSF in watts without a complete context is completely meaningless. Since the engineering math that links case-air resistance to airflow and core temperature is too complex for most tweakers and made even more complicated with variable speed fans, manufacturers simply list CPUs for which the HSF meets or exceeds thermal requirements and let hardware review sites show how much under/over-engineered each offering is.
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