I put both of your emails in one post. I seem to remember replying to this sometime back, what happened to it? ;-)
There's two basic types of PS's; AT and ATX. AT uses a "locked" switch on the PS and ATX uses the momentary switch ON THE MOBO. AT has no switch on the rear of the unit where ATX does, and that switch on the rear of the ATX must be on always in order for the case's front switch to work. As to why you have to turn your PC on or off in a different manner, I can't say. Unless you changed the switch behavior in the BIOS or the 5VSB current is different. The # of fans in a PS actually doesn't have a lot to do with cooling. It's the heatsinks in the PS that are the main determining factor in cooling. Many times a PS with two fans will run hotter than a PS with only one since the former NEEDS the fans due to a lack of HeatSinks. I use the highest rated 400 watt PS which is also the heaviest PS I've ever seen. It only has one fan and also ran the coolest of all PS's tested. This is because it has a massive HS, which is usually one of the ways to tell a quality PS (big HS's). Good brands are Fortron-Source, Enermax, Evercool, Turbo Power & Cooling, and Antec used to be a good brand but I just had a brand new one go out on a customer's PC. I don't know if that was a one-time thing, or their quality has gone down. You usually get what you pay for in a PS. Regarding the direction of air flow: yeah, like Ben said, that's old. I can't even remember a PS that blew air IN. Since the air in the PS is going to be the hottest in the case, the PS takes air from the inside of your case and exhausts that air out via IT, the PS, with a fan blowing OUT. This has a two-fold effect; the air in the CASE is cooler than the air inside the but it is still warm and needs to exhaust, so it goes out via the PS thereby cooling it, and also removing warm air from the inside of a case. Always keep in mind that what you have going in, must be going out. CFM in has to closely equal CFM out. If not, and CFM IN is greater, hot *air* can build up. If CFM out is greater, *heat* can build up since it will be sort of a "vacuum" inside the case. I have a rather warm running setup and I have about 220 total CFM coming in, AND out. It never gets above 75DF (degrees Fahrenheit) inside my case. Sounds like a jet engine, but it's really cool! This is probably overkill for a P4 platform, but not for AMD since they run much hotter. I also prefer a bit overkill than under doing it. http://orpheuscomputing.com/computers/case_mods/1.html . As one can imagine, this DOES act like a "vacuum cleaner" so filters are a must. I haven't added the text yet, but you should be able to figure things out the thumbnail image captions. (There's no page 6 yet). -Clint Happy Thanksgiving to all & God Bless Clint Hamilton, Owner http://OrpheusComputing.com ) http://ComputersCustomBuilt.com ----- Original Message ----- From: "Vern" <[EMAIL PROTECTED]> I was reading about ATX motherboards and it said. ------------------------------------------------------------------------------ a.. a.. The momentary button on the front of the case that powers on the system is supposed to be connected to the motherboard. Unlike AT-style systems, it isn't directly connected to the power supply. Because the ATX motherboard is not physically disconnected from the P/S by the power switch, the motherboard can enter power down mode and be brought back up in a short amount of time. The main shutoff switch is almost always in the back of the power supply, although this feature is becoming more and more scarce with newer units. But holding down the front power switch for a few seconds will also shut off the machine (assuming things are setup that way in the BIOS). Some BIOSes allow an ATX momentary switch to act like an AT power switch and immediately shut off the computer. But the ATX power supply still needs to be attached to the motherboard and not directly to the On/Off switch. ------------------------------------------------------------------------- I don't understand that but after I put a new powersupply in my computer what they call a momentary button doesn't have to be pushed anymore when I turn the computer on like before. Before I had to turn the power on at the surge suppressor and then hit the button on the front of the computer. Now just turning on the power at the surge suppressor starts the computer running. Since I think the computer is running hotter with this PS I'm thinking of getting a different one. I saw a 400 watt with two fans on sale today. Does a 400 run hotter, is that why it has 2 fans? Am I going from bad to worse? <G> Something else I just found. ------------------------------------------------------------- The ATX power supply is different in a number of important ways. ATX power supplies and motherboards function at 3.3 volts or lower, instead of 5 volts, reducing motherboard cost, energy consumption, and heat production. >The fan on the power supply is reversed so that it blows air into rather than out of the case, <which helps keep the case clean and reduces heat buildup. This is necessary due to the high heat produced by the new generation of Intel Pentium II/III and AMD processors. The ATX power supply is turned on and off using electronic signaling instead of a physical toggle switch. This allows the computer to be turned on and off using software control, thus improving power management and energy-saving features. Because of this, ATX power supplies must be matched with ATX motherboards. ---------------------------------------------------- It blows into rather than out of the case??? Vern ============= PCWorks Mailing List ================= Don't see your post? Check our posting guidelines & make sure you've followed proper posting procedures, http://pcworkers.com/rules.htm Contact list owner <[EMAIL PROTECTED]> Unsubscribing and other changes: http://pcworkers.com =====================================================
