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Can a switch replace my computer's power button?
SirPeale:
Zeb: while this will definitely make *any* ATX power supply power up, some motherboards don't like the fact that these have been shorted, and will cause the board to not boot.
SavannahLion:
Zebidee, from what I understand of the PSON line, it is intended to bring a power supply out of a sleep state. Not bring the motherboard out of a sleep state.
When you send an ATX PC to sleep, it either puts a high impedence on PSON or lets PSON float. This forces the PSU into a sleep state, ie it should bring the power lines, except for Standby, down to 0v. The power button on your motherboard is really a soft switch. From almost any state, the motherboard will ground PSON thereby bringing the PSU up to a full power and allowing the entire PC operate.
When you operate the PSU without a MB, you must ground PSON pin to get the PSU to operate properly. (On some, you even need to have a load on the power rail as well!). This is what you're describing.
Here's the rub, there is nothing that specifies that a MB MUST come out of a sleep state if something other than the MB grounds the PSON line. It's possible for some MB's to remain in a sleep state but the PSU will be powered.
There's also another problem. Some PC's (most notably those from Compaq) have all the appearances of an ATX standard PSU and Motherboard, however, the pinout and circuitry of said boards are not ATX compliant nor compatible. On some models, swapping an ATX PSU into these crap boards will do nothing (at best) or pop a few components (at worst). As far as I know, there is no documentation readily available to determine the pinouts of these faux-ATX PSU's.
--- Quote ---This will work like an on/off switch, not like a momentary on/off button that only SOME ATX MBs support.
--- End quote ---
No. not some, ALL. In my entire PC building career, I've yet to encounter an ATX complaint board lacking the the MOM power switch.
From reading your previous postings, it seems that there's some confusion on the different board standards there. In one of my posts, I specifically use AT boards as an example. That is not a typo! I'm not writing AT* to include ATX, I'm specifically writing AT exclusive of ATX. There are many many motherboard standards out there. A small handful include XT, AT, Baby AT, ATX, BTX, and LPX. Wikipedia compares some of the more well known form factors. It is a good launching point to learning the more common form factors you're likely to encounter.
Jack Burton:
You could just mount this switch and when you power on your cab simply rock it back and forth once for turning it on, and again for turning it off. That is, if you only care about the cosmetic function of the switch.
Zebidee:
Thanks SL! That was a fantastic explanation! I appreciate you taking the time to educate me about the sleep-state power-on issue. I haven't encountered an ATX MB like that yet.
Looks like Javery has a bunch of good options to choose from.
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