PC Air Cooling Tips

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PC Air Cooling Tips

Postby dontos » 08 Feb 2009, 07:46

Nearly all PC gamers are aware that good PC cooling is critical for hardware longevity and stable performance. However, there are a few things I have learned through my own experience and articles I have read on this subject, that many gamers are not aware of. This post deals specifically to air cooling. If you find any incorrect info, please point this out.

For proper air cooling of the internal components of a PC, it is critical that there is air flow through the case. There needs to be outside air being drawn into the case through the front and in some cases through a side processor and/or video card vent as well, while air from inside the case is exhausted out the back. This helps maintain a large temperature differential between the internal components of the PC and the air flowing through and around these components, which maximizes heat transfer. Although many internal components have heatsinks equipped with fans, the ability of these devices to dissipate the heat of the components to which they are attached, is ultimately dependent on a fairly larger temperature differential between these heatsinks and the air being drawn through them. If there is insufficient airflow through the case, the temperature of the air inside the case will become too high for sufficient heat transfer to occur and these components will overheat, even if they are equipped with active high capacity heatsinks.

This might lead one to believe that leaving the side panel off a tower case might be a good idea, but there are two reasons I'm aware of for not doing this. First, many of the components in the PC are not equipped with active heatsinks, including hard drives, memory modules, optical drives and the motherboard itself. Without are circulation, heat transfer between these components and the surrounding air will be poor. Second, the fans inside the case and their heatsinks will collect dust more quickly if the case is left open and dust not only clogs fans and heatsinks, but acts as an insulation on the components it covers as well.

So, is it best to have a front case fan, rear fan, or both? The answer in most cases is either both a front intake and rear exhaust fan or a front intake fan only. The disadvantage of having only a rear exhaust fan is that this configuration leads to a slight negative pressure in the case, which leads to air being drawn through tiny openings in the case, which include front case connectors, the space around the power and reset buttons and those present in and around optical drives. To avoid this, one must maintain a neutral or slightly positive pressure in the case. To achieve this condition, you need to have more air being drawn into the case than air being exhausted out through rear case fans and other exhaust fans, such as the power supply fan(s) and video card fan. Installing the highest capacity front fan possible with no rear case fan or a much lower capacity fan at the back of the case will help avoid negative case pressure while ensuring proper airflow. Some cases are equipped with front air intake grills which drastically reduce air flow. If your case has such a grill, you might consider modifying or removing it entirely to ensure that enough cool air is drawn into the case.

In order to reduce noise and energy consumption, some fans are equipped with a temperature sensor which adjusts the fan RPM according to the temperature of the air moving through it. This is a good idea, but only for exhaust fans, NOT front intake fans, as front fans draw the air from outside the case and will not be able to adjust to a higher RPM when the system is running hot. Alternatively, many motherboards support variable fan speed control, which allows you to control fan input voltages and thus speed, according to CPU, motherboard chipset or other temperature. These can be useful, but be careful, as some fans cannot handle too low of a voltage. I do not recommend using this for the CPU heatsink fan. Also, don't use this for fans equipped with temperature sensors (self adjusting).

Image
This is the front case fan on my system. It is a 120mm, deep housing, high capacity (92 CFM = 2.6 CMM max air flow) fan.

In addition to the power supply, video card and small chipset heatpipe exhaust fans, I have a 120mm low capacity (22 CFM = 0.62 CMM) rear exhaust case fan.

Some cases come with an air filter for the front fan, which is quite effective at trapping dust and slowing dust build up inside the case. However, these filters tend to restrict airflow quite a bit and become clogged with dust very quickly. As an alternative, you can use this filter as a template and cut out pieces of fiberglass from an inexpensive furnace filter and use these instead of the reusable filter that came with the case. This material will not restrict the airflow as much as the built in filter, but will become clogged with dust almost as quickly. I can only go a week between changings.

Image
Here is a piece a fiberglass air filter material cut to size next to the front intake filter that came with my case. Notice the dust on the fiberglass after only a few days of use.

Image
Here is how the front of my system looks with the fiberglass filter. Notice that the front grill is removed, as it restricts airflow.
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Re: PC Air Cooling Tips

Postby Blín D'ñero » 08 Feb 2009, 12:12

Interesting!
Installing the highest capacity front fan possible with no rear case fan or a much lower capacity fan at the back of the case will help avoid negative case pressure while ensuring proper airflow.
Aha, that explains why my [good] cases have that. I didn't know it works that way.
[good cases]:
My first PC (prebuilt Pentium 3) has no front fan at all. My next PC's i built myself. All have more or less the ideal situation as seen in the article: my 2 old Lian-Li cases and my current Coolermaster Stacker cases. The Lian-Li's have quite thin front fans. The Coolermaster Stackers (bigtower) have deep front fans.

I''ll put the sidepanels back. :oops: The CPU coolers get clogged quickly and then not only start making more noise, but also the PC's behaviour becomes unpredicatable. One day one PC didn't detect the harddiskdrives during POST anymore. I checked the cables, none was loose. I vacumed the thick cloth from the CPU-cooler and voilá the BIOS hardware check was quick again.
Time to clean the insides again and put the sidepanel back.

Thanks for the article Dontos! :thumbup:
Gaming PC: * Intel i7 4790K * Noctua NH-D15S * Asus Maximus VII Hero * 32 GB Corsair Dominator Platinum CMD32GX3M4A2133C9 * 2× Sapphire Radeon R9 290 Tri-X in crossfire * Dell U3010 @ 2560 x 1600 / 60Hz * Corsair AX 1200W * 7 x WD Black HDDs * Creative Soundblaster ZxR * Asus DRW F1ST * Corsair K95 RGB * Corsair M65 PRO RGB * Steelseries 9HD * Coolermaster STC T01 * Edifier S530 * Sennheiser HD598 * Windows 7 Ultimate x64 *

Workhorse PC: * Intel i7 2700K @ 4.8 Ghz * Noctua NH-D15 * Asus Maximus IV Extreme-Z * 32 GB Corsair Vengeance Pro CMY32GX3M4A1866C9 * Sapphire HD7970 crossfire * 3 x Dell U2410 @ Eyefinity 5760 x 1200 / 60Hz * Corsair HX 1000i * 7 x WD Black HDDs * Creative Soundblaster ZxR * Optiarc AD 5240S * Steelseries 7G * Razer Imperator 2012 * Steelseries 9HD * Coolermaster STC T01 * Edifier S730D * Windows 7 Ultimate x64 *

Workhorse PC 2: * Intel i7 920 @ 3.8 Ghz * Zalman CNPS9900A LED * Asus Sabertooth x58 * 24 GB Corsair Vengeance LP 1600MHz CL9 DDR3 * Sapphire R9 280X Vapor-X * 2 x Dell U2412M @ Eyefinity 2400 x 1920 / 60Hz * Corsair HX 850W * 7 x WDC WD1002FAEX * Creative Soundblaster Z * Optiarc AD 5240S * Steelseries 7G * Razer Mamba TE * Steelseries 9HD * Coolermaster STC T01 * Logitech Z-2300 * Windows 7 Ultimate x64 *
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Re: PC Air Cooling Tips

Postby dontos » 08 Feb 2009, 17:31

You are most welcome. Glad you found this info useful.

One of the major brands of high quality PCs in the American market is Dell. We use mostly Dell systems at my workplace. I have always been impressed by the design of Dell systems, especially the case and airflow designs. All of the Dell systems I have seen have large front fans and front grills which allow for unrestricted airflow into the case. Just more evidence that this is the way to go. I have a Rosewill http://www.rosewill.com/ case and am generally happy with it except for the fact that the front grill air filter cover restricts airflow too much. I tried to modify it by increasing the size of the openings, but finally decided it was best to leave it off. My front fan is a SilenX http://www.silenx.com/index.asp. It was pretty expensive for a fan, but seems to work very well without being too noisy. My rear case fan is a Cooler Master and I'm happy with it as well.
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Re: PC Air Cooling Tips

Postby dontos » 08 Feb 2009, 20:50

Heat transfer in a PC takes place primarily by conduction (heat flow through a solid or fluid) and convection (heat transfer between a moving fluid and a solid). It should be noted that air is a fluid. For example, heat is conducted from the processor to the body of the heatsink. Heat is then transferred from the heatsink to the surrounding air through convection. Convection can be a very efficient way of transferring heat into or out of an object. This is why convection ovens cook food faster than conventional ovens that lack the fans to move the hot air around. Links to some interesting articles below.

http://www.engineeringtoolbox.com/conductive-heat-transfer-d_428.html

http://www.engineeringtoolbox.com/convective-heat-transfer-d_430.html

This article deals deals specifically with convection as it relates to heat transfer in a PC: http://www.pcper.com/article.php?aid=-105&type=expert&pid=7 You don't need to get into the mathematical equations to get a basic understanding of the general concepts involved.

Here is another good article on Wikipedia: http://en.wikipedia.org/wiki/Thermal_management_of_electronic_devices_and_systems

Radiative heat transfer doesn't normally play a significant roll in PC cooling. If it ever does, something has gone terribly wrong! For example, if something is glowing red or white hot and you can feel the heat coming off of it without actually touching it, it is radiating heat!
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Re: PC Air Cooling Tips

Postby dontos » 10 Feb 2009, 02:55

I found this interesting article on peltier coolers. http://www.heatsink-guide.com/peltier.htm Very interesting but not very practical in most situations. Also not very green. These things use a lot of power and require a higher capacity heatsink to go with them, if I understand the article correctly.
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Re: PC Air Cooling Tips

Postby Blín D'ñero » 10 Feb 2009, 04:52

Yeah, not very energy-effient alltogether.

Biggest improvements are in decreasing size and using better materials in the processors so that they run less hot and heat is less of a damaging factor. So: less need for drastic cooling.
Processors getting smaller and smaller, someday beyond molecular level, protons, data not moving through any material at all, but through thin air, micro-laserbeams etc. :cool:
Gaming PC: * Intel i7 4790K * Noctua NH-D15S * Asus Maximus VII Hero * 32 GB Corsair Dominator Platinum CMD32GX3M4A2133C9 * 2× Sapphire Radeon R9 290 Tri-X in crossfire * Dell U3010 @ 2560 x 1600 / 60Hz * Corsair AX 1200W * 7 x WD Black HDDs * Creative Soundblaster ZxR * Asus DRW F1ST * Corsair K95 RGB * Corsair M65 PRO RGB * Steelseries 9HD * Coolermaster STC T01 * Edifier S530 * Sennheiser HD598 * Windows 7 Ultimate x64 *

Workhorse PC: * Intel i7 2700K @ 4.8 Ghz * Noctua NH-D15 * Asus Maximus IV Extreme-Z * 32 GB Corsair Vengeance Pro CMY32GX3M4A1866C9 * Sapphire HD7970 crossfire * 3 x Dell U2410 @ Eyefinity 5760 x 1200 / 60Hz * Corsair HX 1000i * 7 x WD Black HDDs * Creative Soundblaster ZxR * Optiarc AD 5240S * Steelseries 7G * Razer Imperator 2012 * Steelseries 9HD * Coolermaster STC T01 * Edifier S730D * Windows 7 Ultimate x64 *

Workhorse PC 2: * Intel i7 920 @ 3.8 Ghz * Zalman CNPS9900A LED * Asus Sabertooth x58 * 24 GB Corsair Vengeance LP 1600MHz CL9 DDR3 * Sapphire R9 280X Vapor-X * 2 x Dell U2412M @ Eyefinity 2400 x 1920 / 60Hz * Corsair HX 850W * 7 x WDC WD1002FAEX * Creative Soundblaster Z * Optiarc AD 5240S * Steelseries 7G * Razer Mamba TE * Steelseries 9HD * Coolermaster STC T01 * Logitech Z-2300 * Windows 7 Ultimate x64 *
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Re: PC Air Cooling Tips

Postby Blín D'ñero » 10 Feb 2009, 21:33

What to think of CoolerMaster's newest model HAF 932 then? It has huge fans at 4 sides! See gallery

the HAF 932 presents its sturdy sentinel housing and revolutionary High Air Flow structure


  • Front : 230x30mm red LED fan x 1, 700 R.P.M, 19 dBA
    Side: 230x30mm standard fan x 1, 700rpm, 19dBA
    (support 120mm fan x 4)
  • Top: 230x30mm standard fan x 1, 700 R.P.M, 19dBA
    (support 120mm fan x 3 or 120mm x 1 + 230x30mm x 1)
  • Rear: 140x25mm standard fan x 1, 1200 R.P.M, 17dBA
    (support 140mm fan)


230 mm sidefan:
Image

In the top you can choose one 230 mm fan or two 120 mm fans.
Gaming PC: * Intel i7 4790K * Noctua NH-D15S * Asus Maximus VII Hero * 32 GB Corsair Dominator Platinum CMD32GX3M4A2133C9 * 2× Sapphire Radeon R9 290 Tri-X in crossfire * Dell U3010 @ 2560 x 1600 / 60Hz * Corsair AX 1200W * 7 x WD Black HDDs * Creative Soundblaster ZxR * Asus DRW F1ST * Corsair K95 RGB * Corsair M65 PRO RGB * Steelseries 9HD * Coolermaster STC T01 * Edifier S530 * Sennheiser HD598 * Windows 7 Ultimate x64 *

Workhorse PC: * Intel i7 2700K @ 4.8 Ghz * Noctua NH-D15 * Asus Maximus IV Extreme-Z * 32 GB Corsair Vengeance Pro CMY32GX3M4A1866C9 * Sapphire HD7970 crossfire * 3 x Dell U2410 @ Eyefinity 5760 x 1200 / 60Hz * Corsair HX 1000i * 7 x WD Black HDDs * Creative Soundblaster ZxR * Optiarc AD 5240S * Steelseries 7G * Razer Imperator 2012 * Steelseries 9HD * Coolermaster STC T01 * Edifier S730D * Windows 7 Ultimate x64 *

Workhorse PC 2: * Intel i7 920 @ 3.8 Ghz * Zalman CNPS9900A LED * Asus Sabertooth x58 * 24 GB Corsair Vengeance LP 1600MHz CL9 DDR3 * Sapphire R9 280X Vapor-X * 2 x Dell U2412M @ Eyefinity 2400 x 1920 / 60Hz * Corsair HX 850W * 7 x WDC WD1002FAEX * Creative Soundblaster Z * Optiarc AD 5240S * Steelseries 7G * Razer Mamba TE * Steelseries 9HD * Coolermaster STC T01 * Logitech Z-2300 * Windows 7 Ultimate x64 *
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Re: PC Air Cooling Tips

Postby dontos » 11 Feb 2009, 06:30

Well, assuming that the front, top and side fans are blowing air into the case, it looks like this case design is consistent with the principles we've been discussing here. If the airflow is high enough, there shouldn't be too much dust buildup either. However, almost all systems can benefit from being blown out at least once a year, if not more often.
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Re: PC Air Cooling Tips

Postby Blín D'ñero » 11 Feb 2009, 13:40

dontos wrote:Well, assuming that the front, top and side fans are blowing air into the case
Now i get the idea. The biggest 3 sucking in, the small backside fans blowing out.

My Coolermaster Stackers STC-T01's have mounting bracket for optional sidefan of 80 mm (much smaller than the one on the picture above), so it would be noisy! :eh:

Image

Even though the side maze is 300mm diameter, the bracket for a fan is only 80 mm, in the center of it.
Or i should try to creatively reconstruct it so that a 230mm fan fits on it. :)
Gaming PC: * Intel i7 4790K * Noctua NH-D15S * Asus Maximus VII Hero * 32 GB Corsair Dominator Platinum CMD32GX3M4A2133C9 * 2× Sapphire Radeon R9 290 Tri-X in crossfire * Dell U3010 @ 2560 x 1600 / 60Hz * Corsair AX 1200W * 7 x WD Black HDDs * Creative Soundblaster ZxR * Asus DRW F1ST * Corsair K95 RGB * Corsair M65 PRO RGB * Steelseries 9HD * Coolermaster STC T01 * Edifier S530 * Sennheiser HD598 * Windows 7 Ultimate x64 *

Workhorse PC: * Intel i7 2700K @ 4.8 Ghz * Noctua NH-D15 * Asus Maximus IV Extreme-Z * 32 GB Corsair Vengeance Pro CMY32GX3M4A1866C9 * Sapphire HD7970 crossfire * 3 x Dell U2410 @ Eyefinity 5760 x 1200 / 60Hz * Corsair HX 1000i * 7 x WD Black HDDs * Creative Soundblaster ZxR * Optiarc AD 5240S * Steelseries 7G * Razer Imperator 2012 * Steelseries 9HD * Coolermaster STC T01 * Edifier S730D * Windows 7 Ultimate x64 *

Workhorse PC 2: * Intel i7 920 @ 3.8 Ghz * Zalman CNPS9900A LED * Asus Sabertooth x58 * 24 GB Corsair Vengeance LP 1600MHz CL9 DDR3 * Sapphire R9 280X Vapor-X * 2 x Dell U2412M @ Eyefinity 2400 x 1920 / 60Hz * Corsair HX 850W * 7 x WDC WD1002FAEX * Creative Soundblaster Z * Optiarc AD 5240S * Steelseries 7G * Razer Mamba TE * Steelseries 9HD * Coolermaster STC T01 * Logitech Z-2300 * Windows 7 Ultimate x64 *
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Re: PC Air Cooling Tips

Postby dontos » 12 Feb 2009, 04:49

230mm fan! That is one big fan! I thought 120mm was pretty much the largest for PCs. Well, the larger the fan, the more air you can move without making too much noise. I say you should go for it! :thumbup:
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