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PSU AT & ATX

Discussion in 'Hardware' started by Mr.Cheeks, Mar 15, 2006.

  1. Mr.Cheeks

    Mr.Cheeks 1st ever Gold Member! Gold Member

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    There are two types of power supples; 1-AT and 2-ATX, my understanding is the ATX, which obviously is the newer version comsumes less power than the older one AT.

    Question 1: i want to change the power supplies of 3 machine that have the AT units, do simply drop the new ones in or does the case require changing aswell? If so, why so??

    Question 2: what is AT and ATX abbreviated for?

    Cheers...
     
  2. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    Er - these days there are more than 2. BTX is gradualy coming in, and ATX has gone through a number of upgrades.

    ATX does not imply less power - rather it is a different set of interfaces and plugs.

    If you need to change AT PSUs then you need AT PSUs to replace them, ATX will not do.

    The AT PSU is so named because it first appeared in the IBM AT - yes - it is that old!

    Harry.
     
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  3. twizzle

    twizzle Gigabyte Poster

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    As harry said.....

    The atx psu will only suit atx mobos... as the connectors are different between the 2 systems. ATX is one long plug while AT psu's have two smaller molex plugs (p8 & P9). However some of the better PSU's from 2 years ago had both types of plugs on them so would suit either AT or ATX boards. Niether format represents power consumption.. thats what the wattage ratings for! In my system i've got a 600w PSU!! need it for the GFX card and fans :)

    As a side note.... I replaced an old AT psu ages ago. I also had to replace the on/off switch on the case as it was hard wired to the PSU. The replacement PSU had spade connectors for a different type of switch, the old one was soldered direct to pins on the switch.... luckily i had spares at the time... so check that as well when you replace em!
     
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  4. Bluerinse
    Honorary Member

    Bluerinse Exabyte Poster

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    I agree with both previous responses to your questions but I will add my 2cnts.

    ATX apart from what has already been stated also has the ability to turn the system off. I think that is the major advantage and it is because of this functionality that the ATX PSU is not hard wired to the on/off switch. So on newer systems the on/off switch doesn't have a physical on/off state, like a light switch does.

    The power consumed by the PSU is irrelevant. What is very relevant is that the PSU has enough power to *supply* the system. Power has the symbol P and is measured in WATS. So look for power supplies that have more power (WATS) than you require and they will not be over stretched in performing their job.

    Some PSUs are non standard, some manufacturers design their computers so that only their PSUs will fit and some (Dell) have additional plugs on their motherboards too. But usually, if it is an unbranded PC (IBM clone), it will be a standard fit.
     
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  5. Mr.Cheeks

    Mr.Cheeks 1st ever Gold Member! Gold Member

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    Thanks, that i was i noticed, but wasn't too sure...

    That is the only difference i know about, and now the end connections p8/p9. Is there anything else that differs between the two?

    :rolleyes: ??? :rolleyes:
     
  6. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    <cough> The unit of power is the Watt (see here ).

    :biggrin

    Harry.
     
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  7. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    You can't just rewire the plug. ATX also has a power sensing system to guard against voltage drop, as well as standby voltage for the auto-switch on facility (wake on LAN etc).

    The power switch is completely different type between AT and ATX.

    And usualy the PSU case is a different size.

    Harry
     
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  8. Bluerinse
    Honorary Member

    Bluerinse Exabyte Poster

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    You are right of course, it is Watt not WAT - LOL, had a senior moment there. Thanks for pointing that out Harry :D
     
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  9. twizzle

    twizzle Gigabyte Poster

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    Wot! Wat! WATT!!!!!! :biggrin

    or to give it its full title WATTAGE. Symbol P formula VxA=W

    or:- Volts x Amps = Watts.......

    Going back to me roots lol
     
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  10. Bluerinse
    Honorary Member

    Bluerinse Exabyte Poster

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    Twizzle it is V X I = P

    or I squared x R = P

    or V squared / R = P

    V = Voltage, which is measured in Volts

    I = Current which is measured in Amps

    R = Resistance, which is measured in Ohms

    P = Power, which is measured in Watts

    To be pedantic :p
     
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