Posted: Wed Nov 12, 2008 3:12 pm
Irene;Irene wrote:
Any more ideas to keep this sytem cool? Temperatures are still high (as in could be better) and I would like to know how I can keep it cooler without sacrificing silence. Thanks in advance!
Cheers, Irene.
If your going to keep using air cooling that means moving air. Moving air around involves fans normally, fans have noise. Now that being said, having multiple fans means multiple noise sources but normally these fans are like 20 mm to 40 mm or something in that range, there are very large fans in the 70 mm range that move a lot of air but have about the same sound level as a 20 or 40 mm fan. If you can replace multiple fans with a larger one that moves a greater amount of air then you end up with a lower overall sound level but greater cooling capability due to a larger amount of air moving but it doesn't sound like, unless you mod the case in some way, that your set up to handle such larger fans.
I see from your case pics that you do have a place for an intake fan at the front of the case, but I assume youv'e already considered that. If the fan is really contained in the case the noise level is cut down a little and that might help. The trick with internally mounted fans is to keep them from recirculating heated internal case air, a lot of people just mount the fan at the front and assume that its drawing in cool air when its actually also drawing in air from the case also, this decreases the effectivness of the fan and although it is moving air the total volume of the air is warmer then it should be, sealing is important here.
The top of the internal case temp, the correct way to do this temp measurement is with a wet bulb thermometer technique (a lot of people don't know that) and most don't have a wet bulb available or know how to propely do this. The wet bulb will give an indication of air flow at the top by the evaporation action of the wetting solution, this is expressed in a temperature reading vs time (there are charts), basically the faster the evaporation takes place the faster the wet bulb temp drops which can be used to extrapolate an air flow ratio with the higher the ratio the better and faster the air is moving, and generally this is an indication of how well the air is circulated in the case. Heated air setting in the top of the case and not being moved fast enough starts to form a sort of cealing for the cooler incoming air (remember basic science - hot air rises and cool air falls (is heavier) ). The more this cealing increases the less cool air volume in the case because as the cooler air comes in it backs up against this warmer air which has effectively reduced the cooler air volume in the case by taking up space the cooler air could have occupied. In addition where the warmer and cooler air meet it causes disturbances in the air flow sort of like you see on a weather report but on a smaller scale, this effectively causes disruptions in the cooler air reaching the components and may actually cause air to flow away from the areas its needed in and destroys the effectiveness of the air moving devices (the fans). The entire air space in the case should be occupied by the cooler air and very little to none of the warmer air, the case should have a fast positive pressure air flow at the heat source. So warm air collecting in the top of the case and not being removed quickly enough is a bad thing. By removing the warmer air fast enough you could see a few temps difference in the case and with the heated components, maybe as much as between 5 to 10 degree difference in some cases. A lot of people ignore this and most case design ignores this also.
One thing about air cooling, a rule of thumb, the computer overall internally will only be as cool as the air is draws in and circulates but you can increases the efficiency at which this air is used to cool. The trick here is to make the air move across the heat source faster with a positive pressure across the heat source, it will not dramatically lower the circulated internal case air temp but it will remove heat faster leading to a lowering of temps of the heat source (the CPU for example), exahusting the heated air in the case can also not be ignored and is important. This effect can also be created or affected by heat sink design. You can tell if your exausting the heated air in the case fast or well enough by measuring the temp of the heat collected at the top of the case on the case inside (see the wet bulb thing above).
The stock heat sink that comes with the CPU from intel is designed to keep the CPU in an operating range in still air with only the CPU heat sink fan moving any air not at a certain temperature. Adding an unobstructed air flow to this helps a lot and is based on the need for a constant unobstructed air flow across and away from the CPU, giving the air flow an unobstructed shot to the CPU is a prime consideration for air cooling and enhances the capability of the stock heat sink/fan combo. A lot of people think if they lower the temp of the CPU below the designed operating range temp they are doing something good, and they are in some respects of making them feel better, but remember the CPU was made to operate in a certain temp range so its actually not going to be detrimental to operate the CPU in its design range. CPU's cooled below their design range don't necessarily operate better all the time, they mostly just operate cooler. Although CPU's cooled below at least twice their design range do begin to show advantages of faster operation such cooling isn't within the capabilities of most people and start requiring special techniques such as ducting in air conditioning or even going as far as water cooling with frozen or chilled cooling liquids, immersion in chilled cooling liquids, or even a liquid nitrogen heat sink system (I saw one of these once - you don't want to get into it).
If a CPU operating temp range is for example 30C to 80C (I just made these figures up) and it normally runs at say 50 C and you lower the temp to 40C, yes thats great as far as making you feel better about the temp, but it really doesn't do anything for the CPU operation because its still operating in its design temp range.
Some people also put on too much thermal compound between the heat sink and the CPU, you only need the thinnest layer and you don't need any of that fancy stuff like artic silver or anything. The thermal compound layer between the heatsink and the CPU is actually intended to fill very small (most you can't see with the naked eye) gaps and voids in a metal to metal contact. The gaps and voids cause hot spots which affect the overall CPU temp, filling these with a thermally conductive material, that white thermal compound, eliminates these voids by filling them when the surfaces are put together. Something like Artic Silver may make some people feel better (and I know there are lots of claims for what it does), but the presence of metal in a heatsink coumpound might be counter productive when all you need to do is fill the voids and adding metal doesn't do anything really to help this at all. (Yes, I know a lot of people are going to jump on this and tell me how wrong I am, but its true despite what anyone says and any engineer that specializes in heatsink design can tell you the same thing) . That white thermal compound is OK to use, just a very thin layer is needed in the majority of cases, almost thin enough to see thru but fully coating with no spaces in it. (NOTE: Where a metal based thermal compound becomes useful is when the CPU temp is cooled to at least twice its design range temp.). Too much thermal compound is actually detrimental.
So anyway, your left with air cooling if thats your choice. You could do water cooling but some how I don't get the impression you want to get into that. Then your left with the options of increasing air flow, exhausting air, and heat sink fin surface, all of which are going to increase noise level to some degree (if the heat sink has a fan on it). So in the end if your going to stick with air cooling you really have only air movement as an option. Ensure a direct flow of air to the heat source, ensure a good heat sink, and ensure air is in enough volume and fast enough, and ensure air is removed from the case as quickly as possible, and it really helps also if the air your drawing into the case is cooler. Also ensure the case has a positive pressure flow of air at the heat source and that heated case air does not get recirculated and is removed as quickly as possible. At some point with air cooling your going to have to settle for what you can get or do within the capabilities of how far you want to take it. In short, you want your air cooling to be as efficient and as effective as possible.
Yes, in your case option B is a good start, good choice. And I especially like this part of what you said: "After lots of thinking and using some paper to put my idea on, I came to the conclusion that I need to add more exhausts than intakes. " Now your starting out correctly and not just jumping into it like a lot of people do, planning is a good thing here. Very Good.