Has ATX run its course?
As a technical journalist I have been very fortunate to be able to test the latest and greatest hardware as (and sometimes before) it hits the market. Lately I have noticed that our current form factor ATX seems to be reaching the limits of its usefulness. ATX (Advanced Technology Extended) was introduced in 1995 by Intel as the 'replacement' for the AT form factor that was pioneered by IBM in the 1980s.
The new form factor had a better tracing layout and used the 'new' PS/2 connections for mice and keyboards. This replaced the rather large AT connector for keyboards and the 9-pin serial connection for the mouse. The other item that was replaced was the power supply. In the old AT form factor the PSU was much less powerful and used (for the most part) a standard open/closed switch for turning the system on and off.
With the introduction of the ATX form factor we moved to a momentary contact switch for turning the system on and off. This meant that there was no direct disconnect for power. Even while the system was "off" you still had stand-by power going to the board. The momentary contact from the power switch enabled full power and your system was off and running.
Of course, these are very simplistic items to discuss when we talk about motherboard design. If we went into detail this article would grow to several volumes to describe the various virtues of ATX. Intel changed a great deal including extending the board for a cleaner tracing layout. Traces are the small copper lines under the surface of the board; these traces connect the different components and if they are not laid out properly can result in current bleed and cross talk.
But now that we are 15 years from the introduction of the ATX form factor and have seen many new variants come out (micro-ATX, Mini-ATX, E-ATX, etc), has ATX run its course?
ATX's current revision was born back in 2007. This was version 2.3 and represented a number of changes over the years (the exact number of revisions is a matter of debate as there were a few versions that ran concurrently). ATX versions 2.2 removed the 4-pin Aux power connector and added it to the PSU, moving the PSU from 20 to 24 pins. However, ATX 2.3 put it right back on and in many cases added 4 more pins to cover the power needs of the board. The 5v and 3.3v tolerances were increased in addition to a number of minor changes to address increased power requirements.
Now, however, we are seeing motherboards that use more than even the extra 8-pin 12V Aux connector. In the past month I tested a board, the MSI Big Bang X-Power that used two 8-Pin Aux connectors and a 6-Pin.
The same thing with the ASUS Rampage III Extreme, it required two 8-pin Aux connectors and two 4-pin Molex!
So with this in mind, we have to wonder, how many revisions of the ATX spec for motherboard design and PSU is enough? Do we need to move to a new form factor and PSU spec? We asked around to see what the industry thought about this. Flip over to Page 2 to see what they say.