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Thread ID: 99937	2009-05-20 05:44:00	Which direction does AMD and INTEL fans move air	nedkelly (9059)	Press F1

Post ID	Timestamp	Content	User
775425	2009-05-21 05:11:00	Actually, our Megabyte friend makes a lot of sense, and I have long questioned the industry standard methods of cooling. He is correct with his explanation of the positive pressure case being better for achieving heat transfer from the heat sink and CPU to the air, although the advantage is very small. It is also correct that a positive pressure case (with air intake part way up the wall of the case) will collect less dust inside. Gravity results in most dust ultimately settling on the floor, or the desk. Basically whatever surface the computer sits on will also be a place that gathers dust. A negatively pressured case will suck in air through all gaps, and the gaps near the floor/desk will have more dustto offer up to the inside of the computer, in addition to all the airborne dust. A positive pressure case will only pick up airborne dust. Dust from floors will be greater than dust from desks. Having a CPU fan scattering hot air all over the rest of the inside of the computer is stupid. It essentially turns all the components and the case itself into a radiator of heat. Ideally, the CPU fan should be moving air straight from the heat sink to the exterior of the case. This would keep the entire system running cooler. Our current systems are just a hangover from the days when all that was needed was a single exhaust fan in the PSU (not even a CPU fan), and the design has not been properly overhauled since.	Paul.Cov (425)
775426	2009-05-21 05:19:00	My case has a 100mm fan in front that sucks cold air in and another at the back that sucks hot air out. Only problem . my ash tray sits right in front of the front fan. The smoke rises verticaly and when it reaches the fan it turns 90* straight into the case. I've often wondered what it would do to cooling if I reversed the fans and sucked fresh air in the back and out the front if you reversed the rear and front case fan the case temp would go up. this is because your forgetting about the PSU fan. PSU fan blows hot air out which will simply get sucked in the rear fan. that air in the case will simply get blown out by the PSU fan again, around around in circels. the front fan will pull a little bit of air thorugh the case but over all you will have dropped the amount of air flow and the air that does come in will be hot air. obviuosly how much air depends on case fan sizes and how they fight/work with each other. easiest way is move the ash tray. have you seen what smoke does to a pc? its amazing some last as long as they do. with back would fans i used to see a fair few of them becasue the PSU had overheated and died. if they didn't have a rear fan, just blocking up the fan location used to drop the case temps. 1024KB- heat sinks have to be designed specially for reversed fan setups. one of the good old ons was the alpha heat sink. in its day it was huge with wide fine spacing and a suck fan arrangement. but higher heat and the need for close fins to get big surface area means suck fan arrangement won't work. lots of thin close fins require a bit of force to get air to move between all the fins, hence the use of high speed fans in blow arrangement. swap the fan over and you will just get a partitial vaccum, no air MASS going past the fins hence not much cooling.	tweak'e (69)
775427	2009-05-21 05:41:00	Having a CPU fan scattering hot air all over the rest of the inside of the computer is stupid. It essentially turns all the components and the case itself into a radiator of heat. Ideally, the CPU fan should be moving air straight from the heat sink to the exterior of the case. This would keep the entire system running cooler. not by much at all. exhaust air temp off the cpu heatsink is not a big amount due to the decent amount of air flow through it. plus its also mixed with more case temp air then sucked out shortly after. its not really being blown around the case. the few extra degrees it can make to other componants is nothing that they can't handle. (eg ram and power regualtors).	tweak'e (69)
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