Difference between at and atx motherboard

at and atx mother board

AT AND ATX POWER CONNECTORS 


SMPS standard model provides different power supplies. They are

(i) AT power supplies
(ii) ATX power supplies.

(i) AT POWER SUPPLIES



    The SMPS of AT style supplies D.C outputs to two and four connectors containing six and four pins, respectively former one ie., two 6 pin connectors which J8 and J9 are transfer D.C power connections to the motherboard. The voltage they supply includes + 5, -5,  + 12, – 12 and POWER GOOD signal. While the latter one ie. 4-pin connectors has similar sizes shapes and they carry D.C power to floppy disk drives and hard disk drives.

AT STYLE POWER SUPPLIES
PIN NOCONNECTORCOLORSIGNAL
1P8OrangePower good
2P8Red+5V DC
3P8Yellow+12V DC
4P8Blue-12V DC
5P8BlackGround
6P8BlackGround
7P9BlackGround
8P9BlackGround
9P9BlackGround
10P9Yellow-5V DC
11P9Red+5V DC
12P9Red+5V DC



      The POWER GOOD signal in SMPS can be specified as a special flag to the CPU. It checks whether output voltages are stable and utilized by the CPU. The CPU gets reset when there is no POWER GOOD signal. On the other hand, in older PCs switch to power-on, the SMPS is attached outside the system box. And in new PCs, it is incorporated in the front panel on the system box. In addition to this, it also includes a cooling system in the form of a fan that rotates until the power is turned-of

(ii) ATX/NLX POWER SUPPLIES

      ATX/NLX POWER SUPPLIES
PIN NOCOLORSIGNAL
1Orange3.3 V
2Orange3.3 V
3BlackGround
4Red5 V
5BlackGround
6Red5 V
7BlackGround
8GreyPW-OK
9Violet5 V
10Yellow12 V
11Orange3.3 V
12Blue-12 V
13BlackGround
14GreenPS-ON
15BlackGround
16BlackGround
17BlackGround
18White-5 V
19Red 5 V
20Red 5 V

    The ATX/NLX style SMPS uses a 20-pin connector to supply D.C voltages such as + 5 V,-5 V, + 12V, and 3.3 V. Few motherboards include both connectors i.e. AT SMPS and ATX SMPS, depending upon the type anyone can be used. The ATX NLX has three special signals. They are,

(a) PS-ON

(b) SVSB

(c) PW-OK

(a) PS-ON

It serves as an input to SMPS. When PS-ON is low, the SMPS output is supplied, or else the output is turned OFF. The software usually generates the signal.

(b) 5VSI

It is a standby voltage and carries the power to special circuits. It supplies the voltage at the time when SMPS and the system are in an OFF state

(c) PW-OK

It is a POWER GOOD signal.

What is an ATX Cabinet or ATX Case?

ATX CABINET

at and atx cabinet

  ATX Cabinet is the enclosure that contains most of the components of a computer. ATX cabinets with amps are available. Micro ATX motherboard is at the top and peripheral connectors go to the panel located at the rear of the case and the USB ports at the top of the atx Cabinet. AT and ATX’s fans are also back and front. And The power supply is the bottom back.