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#21
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CPU Cooler designs?
On Tue, 26 Sep 2006 20:55:53 +0100, Gerry_uk
wrote: Hi kony, A properly set up system has no need for the side intake and is usually as well off having it blocked completely. Perhaps, but here's something to try. Run your ordinary ATX fan cooled PC for two hours in the summer including some time under load. Measure the CPU and MB temps, then remove the side panel near the CPU, watch the temps FALL like a brick! If your ambient (room) temp is much higher in summer, it might be better to make the room hospitible to the user, and have the system benefit as a side-effect. If the system is intended to be used in hot environment, this should be taken into account when designing or modifying the system cooling. If you take the side panel off and get lower temp, the real question is whether the temp was too high before you took it off. The secondary issue (still quite important) is whether the OTHER parts are as cool. In general, taking the side panel off will tend to make the HDDs and other lower-front quadrant parts run hotter than with it on. Never forget that the CPU is not the only part that needs to run cool enough, it is merely the one most people are overly fixated on- and yet it has a large heatsink. A balanced system, properly set up, will have a CPU heatsink of acceptible size. It should never be necessary to remove the side panel and enough airflow to keep the other components cool enough, is likewise enough airflow to keep CPU cool enough. If it is not cool enough and the other components are, the solution is a heatsink upgrade or to increase chassis airflow (but the latter increases noise more than the former, assuming "heatsink upgrade" doesn't mean merely choosing one with a higher RPM fan on it). |
#22
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CPU Cooler designs?
On Tue, 26 Sep 2006 22:19:22 -0500, "Vanguard"
wrote: "kony" wrote in message news On Mon, 25 Sep 2006 22:38:03 -0500, "Vanguard" wrote: Blowing air out the side panel means you are sucking in pre-warmed air over the CPU before exhausting it. Blowing air into the case directly at the CPU means you get the greatest temperature differential. Since the PSU is nearby, the air warmed by the CPU gets drawn out and exhausted through the PSU rather than over the memory sticks or chipset. Blowing air in (or having no side fan at all) results in the most pre-heated air flowing over the memory or chipset. Granted, the air might be slightly cooler. Slightly cooler? Try 15 C cooler. Only if the case wasn't designed properly. CPU temp rise is in direct correlation to chassis ambient temp and the chassis should not be 15C hotter. If the chassis is that hot, the other parts were suffering too and putting in the side duct may make them even hotter. Remember the system is not only comprised of a CPU, if the CPU as hot, so are other parts that you may not be monitoring actively- and if you aren't monitoring them actively, it can be even more important to have a larger thermal margin. While my room temperature is 20 C, the inside temperature is 35 C (no, I haven't gotten to modding my home PC's case yet). What are you using to determine the case temp? If you rely on the "system" or "case" temp resport via software, I presume you realize that is often not the actual chassis air temp but rather, of a different chip that produces it's own heat. Actually I prefer a quiet PC so I let Speedfan slow down the fans which lets the inside get hotter unless temperatures exceed the configured thresholds whereupon the fans speed up and are more noisy. Cooler internal temperatures would mean cooler air over the CPU (and GPU). Having to push warmer air over the CPU means less efficient cooling. If I can get MORE cooler outside air inside the case then there would be fewer times when Speedfan would have to speed up the fans. There is no need to speed up the fans at 35C, so there is either more significant information lacking in your description, or another issue (which is likely chassis airflow, if the actual chassis air temp is 15C above room ambient). Even if the latter is true, we can ignore the CPU temp and not throttle up fans, rather focusing on the other parts. Remember that the CPU is more heat resistant than many of them, and has a longer expected lifespan too. The key to reducing warm air flowing in circular or counterproductive directions is to not interfer with the time-tested and proven chassis airflow pattern from bottom front to mid-top rear. Time-tested? Yes Time has shown that the ATX case was NOT designed for best cooling. "Best" is arbitrary if you only focus on CPU temp, particularly when you describe above a CPU that is not even remotely close to overheating! It provides absolutely no zoning of airflow. Wrong, it does far better than having a side duct. WIthout the side duct there is a clear airflow path from bottom front to mid-top rear. Add the side duct and the bottom front will necessarily have lower airflow rate. In fact, it stupidly enforces turbulence because of the twisting required for the airflow, Turbulence ON the parts being cooled is exactly what you want. Turbulence in the rest of the case is minimal, it is proven so and WAS TESTED when ATX was spec'd. They didn't ignore cooling of everything but the CPU though, which seems to be what you are doing even when CPU is far cooler than it needs be. and turbulence is resistance to airflow. Inside a chassis that is much larger than the intake or exhaust areas, the effect of turbulence is minimal, beyond consideration. Do you see any ATX-style cases that have channels built in to keep flat cables out of the way so they don't block the airflow? It is a marketing feature unless the system integrator has no idea how to route cables properly. Plenty of system builders have demonstrated, millions of times, that a case with ribbon cables and no channels built in will run fine IF the primary considerations are considered- and they don't require a side duct, rather as mentioned previously, the side duct interferes with airflow around cables by reducing the amount of airflow in this region. IF your side-duct was blowing out of the case instead of in, it would increase the airflow around drives, cables, but this then decreases airflow around (many if not all) CPU VRM circuits, and out the PSU, and possibly through the CPU heatsink too. Why did they design it so hard drives could be shoved against each other (so there is no airflow between them)? Your proposition of the side duct does not change this, only further reducing airflow there. Further, you only assume they designed to have drives "shoved up", when in actuality it was case manufacturers that only tried to put the most drives in the least space possible that resulted in the "shoved" scenario. Low front intake is okay for drives in the lower cage but not in the upper drive cage. ATX (without modification) is a poor design for cooling. Drives in the upper cage are also cooled worse if you introduce a side duct, unless you had the duct opposite the rack (which is almost never done, it's far lower). A better question is why you feel they are not cooled well? Optical drives do not need a lot of airflow, those that are particularly hot running tend to have a fan in their casing but once designs that weren't so hot were produced, the fans were eliminated. If you have a hard drive up there, you are choosing to not adhere to the normal component placement and as such, are taking it upon your self to provide a front intake (perforated if not actively fan cooled) front faceplate to accomodate this change in drive location. ATX does accomodate drives fine, if you don't assume some poorly made case defines what ATX is, rather than the truth- that ATX is the definition and the poorly designed case made other design mistakes. By reducing the bottom front intake rate, by use of a side intake if not another method, there are lower velocity flow everywhere except into the 'sink. The exhaust fans will exhaust at same rate (providing front intake was sufficient) but a short-loop is created, any air not exhausted into the air most immedate to the exhaust fan will take a longer path till exhausted, and slower. Short loops are exactly what are needed for zoning the airflows to minimize them from intermingling with each other. Short loops are robbing the lower front area of the case, unless you then add a front mounted fan which increases noise level and then reduces the effect of the side duct. Intermingling is exactly what your side duct causes, because you prevent the airflow from going in the proven effective path from bottom front of case towards the rear, by reducing the flow rate significantly. This is proven fact and was taken into account and measured when ATX was spec'd. Cool the hot stuff first with direct outside air and expel it immediately. Wrong, you have to consider the pressure gradients, to have suction sufficient enough to intake air into the front of the chassis unless you add another fan which has drawbacks as mentioned above. Go ahead and add several addt'l fans if you like, but if you do that you again eliminate the need for the side duct by more directly addressing the problem with your case (if it actually has 15C rise in internal air temp). Actually, if you case has that high a rise, it would possibly indicate the problem in airflow that I've already described. Side intake is mostly Intel's attempt to ship cheaper heatsinks with P4, particularly Prescott CPUs. Wrong. Side intake was to circumvent the ATX spec's poor airflow design. You have supplied zero evidence of this, thus far only describing a chassis that is overheating, then that the CPU is overheating as a result unless you add a side duct. You have still ignored the REST OF THE OVERHEATING PARTS. A CPU can run at 60C for years, longer than parts like HDDs, fans, motherboard can. The CPU is not the only part that needs cooled Exactly, so why use the same airflow to cool EVERYTHING? "Same airflow" means a pseudo-linear path, because this maximizes flow rate per fan over everything. You are ignoring a primary detail in system cooling, that your CPU was not described as overheating and you are not reporting temps and temp changes of any other parts. This is a HUGE MISTAKE and quite often why hard drives die. ATX is a poor design for cooling. Modders knew that for a long time before case makers starting adding the extra intake/exhaust ports. Actually, the vast majority of systems sold and running today are OEM systems, and they do not have all these changes the modders made. It may be true that if a so-called modded had a poor generic case, they needed to make "some" kind of change to it, and they may not make the best choice from a airflow:noise ratio perspective, OR they might be overclocking without a suitable heatink, or as mentioned several times already, they may not be focusing on any parts temps except the CPU and system (actually another chip temp). BTW, I mod plenty of cases, even early ATX that had no aim of cooling today's higher heat parts, even overclocking parts quite a bit as a hobby and do not need to do these things you imply are important- because I actually meaure temps of ALL parts that heat up and observe the temp changes. Most modders don't do this, they just throw a lot of fans at a situation and end up with a loud system... certainly louder than Dell et al. OEMs produce. It is possible to add enough very large, low RPM fans to offset this and still have low noise:airflow ratio, but then the expense goes up for quality fans or the maintenance of these cheap fans increases, and fans mounted on exterior walls of the chassis always let more noise escape, because there's nothing to really "escape", they're already facing the external room. In fact, I've seen CPU and case temperatures drop in some cases by reversing the backpanel fan so it is an intake fan rather than an exhaust fan (its normal position) but you need to test in your own case. This should never be done, it necessarily increases temps of other parts (unless the case was otherwise unusual in it's airflow before this fan was flipped over). Not if you add MORE venting, like adding a top grill LOL. A top grill is almost never a good idea. If the case were incredibly poorly designed to it was starving for air, or had a very very poor PSU that was overheating more than anything else, having the top vent increase airflow might seem to help, but still robs the lower front quadrant of airflow, it is a poor choice in resolving the prior choice of a poor case in general. Such a modder shows they have made two mistakes, choosing a bad case then choosing a lesser effective mod and one that may actually reduce airflow in other parts of the system. There are plenty of examples of ATX cases that run fine without these kind of misguided hacks. You are attempting to suggest ATX is a problem when ATX was not the variable, rather the other aspects of particularly poor cases were the variable. It doesn't really matter if you agree, there are plenty of examples of ATX cases cooling fine. The most significant problems with ATX are these two: 1) CPU manufacturer that provides a cheap heatsink that needs help. The word Prescott comes to mind and the entire industry has already acknowledged it and praised subsequent CPUs for not having this known problem. 2) Video cards with very high heat and small heatsinks so as to not block one or more PCI slots. In summary, I will repeat what I wrote above as it is key in your misunderstanding: You are attempting to suggest ATX is a problem when ATX was not the variable, rather the other aspects of particularly poor cases (and system setup) were the variable. When someone takes on the role of system designer, selects parts that don't work very well, only then do they have to find a solution and what you have described is an attempt to band-aid the problem instead of addressing it directly, then ignoring the effects on anything but CPU that was not overheating at all per your description. I have demonstrated exactly what i have described far too many times to count, as have the majority of systems running today made by most OEMs. |
#23
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CPU Cooler designs?
"kony" wrote:
Turbulence ON the parts being cooled is exactly what you want. Turbulence in the rest of the case is minimal... You've done a 180º on THAT, Kone-head. Inside a chassis that is much larger than the intake or exhaust areas, the effect of turbulence is minimal, beyond consideration. You've done a 180º on THAT, Kone-head. I think I'll call you "One-Eighty Kone-Head". *TimDaniels* |
#24
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CPU Cooler designs?
Keep in mind that the manufacturer's design of the case
must conform to FCC spurious emission requirements which preclude opening large holes in the chassis. I really don't know how the "game machine" manufacturers get away with their plexiglass sides - unless those sides have a metal film or the manufacturers' low volume production exempts them from FCC requirements. *TimDaniels* |
#25
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CPU Cooler designs?
On Wed, 27 Sep 2006 11:28:51 -0700, "Timothy Daniels"
wrote: "kony" wrote: Turbulence ON the parts being cooled is exactly what you want. Turbulence in the rest of the case is minimal... You've done a 180º on THAT, Kone-head. Nope, read more carefully. Inside a chassis that is much larger than the intake or exhaust areas, the effect of turbulence is minimal, beyond consideration. You've done a 180º on THAT, Kone-head. I think I'll call you "One-Eighty Kone-Head". I think I'll call you miserable. You torment yourself and falsely assume trolling will help. Obviously not Tim, or it would've done so already. |
#26
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CPU Cooler designs?
On Wed, 27 Sep 2006 11:34:13 -0700, "Timothy Daniels"
wrote: Keep in mind that the manufacturer's design of the case must conform to FCC spurious emission requirements which preclude opening large holes in the chassis. No they do not have to conform! An assembled, whole system must pass such tests but a case alone does not have to. I really don't know how the "game machine" manufacturers get away with their plexiglass sides - unless those sides have a metal film or the manufacturers' low volume production exempts them from FCC requirements. See above, it doesn't have to meet a spec because it has no power plug and produces zero emissions AS-SOLD. |
#27
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CPU Cooler designs?
Gerry_uk wrote: Hi, As I understand it, most ATX style PC setups have a fan above the CPU that blows air down onto the CPU to keep it cool, and the hot air bounces around inside the PC case until it can find an exit (if it's lucky). As I see it, there are two problems with this, darn right!!! but no how you think. The fans have been installed backwards!!!!!! The (CASE FAN) fan above the CPU is an exhaust fan. It blows the hot air out of the computer. There is also an intake fan on the front at the bottom. Usually hidden "thanks" to the cases with snazzy fronts and some tiny hole somewhere stopping you seeing how it can get any air in. But if you open the computer you'll see a space there to fit a fan. this also makes sense because hot air rises. I'm sure I once saw a picture in a document called AMD cooling requiremetns or something, that showed an arrow indicating the directino of the air. Anyhow, it is like that. a) unless you have a vent in the side of the PC case, the air being taken in by the CPU cooler will not be cool, because it's air from inside the PC case? Interesting point. I think I saw in a scott mueller video that CPU heatsinks do **Suck** air downwards and blow it out the bottom. I almost forgot about that. Where did you read that? b) the hot air from the bottom of the heat sink ends up warming up the Motherboard? I was looking at the Dell CPU coolers of the GX280, GX620 workstaions (Intel P4 / Pentium D) and the PE2400, PE 2600, PE2800 servers (Intel Xeon). The design is completely different. The air is sucked in from the front of the case, straight over the CPU and out of the back - how cool is that? Pretty cool, and there's hardly any noise either. the front of the case is nowhere near the CPU. And generally the fan is at the bottom front. The CPU is at the back of the case near the top, just below the PSU. It's impossible for a front fan to suck air in over the CPU. It's far away. It just sucks air into the case. Unless this server is somehow unlike any computer i've ever seen. But if it uses an ATX MBRD then I find that hard to contemplate. You should have included a picture - if you could find one. |
#28
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CPU Cooler designs?
"kony" wrote:
"Timothy Daniels" wrote: Keep in mind that the manufacturer's design of the case must conform to FCC spurious emission requirements which preclude opening large holes in the chassis. No they do not have to conform! An assembled, whole system must pass such tests but a case alone does not have to. So now you're pointing out that an empty case does not have to conform to FCC requirements. What an insightful comment! Wot an idiot you are. Even if you have nothing valuable to add, ya gotta keep spewing. *TimDaniels* |
#29
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CPU Cooler designs?
"kony" wrote:
"Timothy Daniels" wrote: "kony" wrote: Turbulence ON the parts being cooled is exactly what you want. Turbulence in the rest of the case is minimal... You've done a 180º on THAT, Kone-head. Nope, read more carefully. Riiiiight - as you've said before, "turbulence ON the parts is what aids their cooling, NOT turbulence hitting the parts". Please differentiate between the two for us Kone-Head, you'll say ANYTHING FOREVER to be the last one posting. Start spewing.... *TimDaniels* |
#30
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CPU Cooler designs?
On Thu, 28 Sep 2006 19:12:01 -0700, "Timothy Daniels"
wrote: "kony" wrote: "Timothy Daniels" wrote: "kony" wrote: Turbulence ON the parts being cooled is exactly what you want. Turbulence in the rest of the case is minimal... You've done a 180º on THAT, Kone-head. Nope, read more carefully. Riiiiight - as you've said before, "turbulence ON the parts is what aids their cooling, NOT turbulence hitting the parts". Please differentiate between the two for us Kone-Head, you'll say ANYTHING FOREVER to be the last one posting. Start spewing.... Turbulence before the air gets to the part, decreases chassis intake and exhaust rates to whatever extent this turbulence persists. Turbulence on the part is necessary for best effectiveness of the sink. The goal is to keep the air moving at good rate, only slowed down when meeting it's purpose. Let's look at another example- You have a lizard that eats insects. It's using camouflage to sit still and wait for the insects to come near it. It wants, even needs if to be able to eat enough, for the insects to approach at a certain rate, then for those insects to sit still at least long enough to be captured by it's tongue. If the insects each in turn, sat still for a long long time at each interval prior to moving close enough for the lizard to eat them, which is a lower average rate of travel, the total insect:time ratio is lower. So the lizard wants them coming as fast as possible, but the shorter the time spend in front of the lizard, the lower the insect:capture ratio is. The lizard may survive if there are enough insects that their average rate of travel doesn't matter, and likewise a computer if someone stuffs extra fans in it to combat the excessive turbulence extraneous to hot parts contact. The optimal solution is not to add those fans, not to interfere with their flow rate either- it's to retain maximum flow to the parts by the cooling system, and the rate of exhausting that hot air out of the system. The (average) ambient temp of the semi-enclosed system depends on this intake:exhaust rate, so if the total I/O airflow rate is reduced, it heats up less for each subsequent time interval because it is closer to the temp of the part surface it had just been in contact with. Naturally I don't expect you to agree at all Tim, you were still trolling as usual but maybe other people won't be as confused as you are about these OBSERVABLE phenomena. Again Tim- the reason why cases have the holes in the front is to keep the ratio of opening to opening length minimized for reduction of EMI. It would be a trivial thing to set a metal stamp to a more complex pattern to increaes turbulence if that were their goal instead. |
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