AT vs ATX power supply?

[weshuang]

I unwittingly bought at ATX power supply and have been trying to get it to work with an AT mobo. Just won't work, and it's a simple swap of a finicky power supply with the new one. The ATX power supply has an extra connector that the old doesn't have - a four-hole +12V power connector. There's no spot for it on the mobo. Should the power supply be compatible?

 

[LED]

It won't work as the ATX PSU is much more advanced and runs cooler. There are so many features that are missing with the AT Mobo you have so return it and get an AT Unit. The ATX uses the MoBo to turn it on, advnced Software and other factors so you would also need a new Case if your thinking about upgrading the MoBo because of the buttons on it. I dare say eventually you will be going this route so I would suggest looking for a used AT PSU and get ready to upgrade.

 

[weshuang]

Thanks, LED! For anyone else who needed info on this, I'll also post a reply e-mailed to me that was very specific.

>><FONT face="Courier New">The connectors for the disk drives are identical, but the ones
for the motherboard are completely different. Any 6-pin connector
is mechanically compatible with the AT motherboard connectors, but
don't plug it in because its pin definitions are very different
(black = ground, orange = +3.3V, red = +5V), and damage could result
if the supply is turned on. AT power supplies are turned on by
connecting 120VAC to them through a switch, but ATX supplies are
normally partially on all the time and are turned on fully with a
low voltage signal from the motherboard. You can turn it on by
shorting pin 14 (green wire) to ground (black wire). The front panel
power switch is completely different. With AT supplies it handles
high voltage and high current, is double poled, and latches in each
position. With ATX supplies it's low voltage, low current, single pole,
normally off and momentary, like the reset button.

There are adapters to allow using an ATX power supply with an AT
motherboard, complete with power switch, and I saw one at Fry's for
under $10. But it may be better to just find a surplus AT supply
(www.directron.com has some) or a used one from an independent
computer shop that's been in business for a long time. By the
way, Enermax AT power supplies weren't always that good because
they lack a component meant to reduce turn-on surges. </FONT>

 

[weshuang]

Thanks, LED, and also to the other who responded!

It turns out that I was really confused about what AT vs. ATX form factors meant. I was thinking for some reason that ATX were the micro form factors (I realize now, I think, that those are referred to as Micro ATX), and that AT were the full size boards.

My problem now is trying to figure out what the form factor is for the system whose power supply I'm trying to replace. Unfortunately, its a Dell, and their support page doesn't provide the form factor. Is there any way to tell by looking at the motherboard? The CPU is a Pentium II. The only other clue that I can think of is that the old power supply doesn't have a rocker power switch on the back of it, which the new ATX power supply does.

In any event, I can't get the ATX power supply to work with that system, and I somehow don't believe that its DOA.

 

[svidanag]

Dell's powersupplies are mostly proprietary, meaning you have to go through them to get a replacement. Call them up and ask.

 

[weshuang]

D'oh! Stupid dell.

 

[LED]

Well apparently this needs more input or output as be the Case cause I got these emails from

LOL...although English is a 2nd language for me I can see that the word advance has a different meaning to you then Webster...Next time I call up my Puter via ATX true-450wt PSU to turn on and run some Programs before I get home or when it shuts down because my CPU ran too hot from overclocking...I'll wish it had an equal AT PSU and what MoBo's they support...Any more bytes from you will not be answered as it's 1 waste of time that others can not share the wealth of knowledge here so I once again invite you to post instead of me wanting to Copy and Paste this there... that's why I post on an open Forum so that others may gain knowledge, debate and chose. Your not some Esoteric Guru that knows more then others...some probably but all NOT!

Being criticized from someone unknown (not the 1st time) means very little and BTW I have a few older VCR's and BETA's @ the studio that have no programming or remote turn on and when they added them it became more advanced.

Better design PSU??? probably EPS...
Enjoy whoever you are


-------Original Message-------
> From: Unrealaddresss@wmconnect.com
> Subject: Re: Re: AT vs ATX power supply
> Sent: 19 Feb 2003 20:15:45
>
>
>
> >>It won't work as the ATX PSU is much more advanced and runs cooler.
> >
> > That has got to be one of the wierdest answers I've read.
> > Cooling may or may not be better, and the only extra features
> > are +3.3V, +5V standby, and remote turn-on, none of which
> > could be considered "advanced."
>
> >Dunno who you are but I'd suggest you read up on the differences
> >a little and the fact that an ATX PSU can be controlled by the
> >BIOS and other software whereas the AT can not I'd consider it
> >advanced ...not to mention the fact that it took over AT's, runs
> >quieter, has better warranty's, and comes in better designs, end
> >result more advanced and runs cooler wt for wt!!
> >
> >Have fun and if you want to debate the issue I invite you to post
> >on that thread then I may post some links for you.
>
> I just didn't want to criticize you in public.
>
> Remote turn-on is hardly an "advanced" feature, as every VCR
> made since 1980 and every remote control TV ever made has had it.
> Even a few AT supplies were made with it. Real advanced features
> would be things like 90%+ efficiency, independent current sensing
> for each output line, including something similar to plug & play
> (load would specify maximum current), alarm signals (more than
> the Power Good signal but something that would allow the computer
> to warn the user and perform an orderly shutdown), control by
> digital signal processor, and fault monitoring that notices
> changes in operational details, not just excessive current, power
> and voltage (which a DSP could handle).
>
> What better designs have you seen in modern power supplies? The
> only ones I can think of are voltage regulation by current-mode
> control rather than solely by voltage-mode control and the more
> widespread use of MOSFETs (both high side and to replace diodes
> on the low side), but some AT supplies from 10 years ago had that
> as well. There have been cosmetic changes, but I doubt you're
> referring to anything that frivolous.
>
-------Original Message-------


Now you are nitpicking bytes from the complete e-mail so 1 more response from you and this ridiculious chain of events will deserve a copy and paste on the thread so others may see ...Get 1 Grip and move on or "advance" without you choosing the definition of the word!!!

Good bye, Good Ridance, and of course Good Luck


-------Original Message-------
> From: Unrealaddresss@wmconnect.com
> Subject: Re: Re: AT vs ATX power supply
> Sent: 20 Feb 2003 05:31:08
>
>
> >Next time I call up my Puter via ATX true-450wt PSU to turn on and
> >run some Programs before I get home or when it shuts down because
> >my CPU ran too hot from overclocking...I'll wish it had an equal AT
> >PSU and what MoBo's they support...
>
> That doesn't change the fact that those are not advanced features
> that were not found in power supplies decades ago, although PCs
> didn't have them. You should realize that for the last few years there
> have been industrial power supplies with built-in NICs for control
> and monitoring purposes, some of the newest using processors
> not only for on-off control and monitoring but even for the regulation
> itself. I expect ATX supplies to eventually be available with something
> similar to this, only with USB instead of ethernet.
>
-------Original Message-------
I'm not nitpicking, just pointing out that the features you consider
to be advanced are really not, and PC supplies are thought to be
fairly primitive compared to other switching supplies designed
in the past few years, which waste only half as much power.

Maybe this knowledgeable individual will come and join this thread or should I post the ISP addy and Server from qmail via aol wm.connect???

 

[weshuang]

Well not that this makes any difference, but both answers were helpful to a non-techie like me. As Arthur Clarke said, any sufficiently advanced technology would be indistinguishable from magic. Consider me a Cro Magnon...