Resetting ATX Motherboards

ATX motherboards were first introduced in 1995 primarily as a smaller and more efficient form factor. Along with this evolution away from the AT motherboards, the RESET buttons were mostly removed and that function was incorporated in the new push button type ON/OFF switch. The push button switches operate on a momentary closure concept verses the mechanical breaker type switches on the AT motherboards.

The power on the ATX boards is actually controlled through electrical signals from the push button or other software. This is all well and good as long as there is power to the machine. It is only when power is lost or the machine hangs that things get a little more hairy.

Pushing the button to turn the machine OFF doesn't necessarily mean that the machine is OFF, it may be just sleeping, unless you pushed the button for xx seconds. Likewise, when power is restored, it doesn't necessarily mean that the machine will power ON, you may have to push the power button again to power it ON. Machines with certain chip set/BIOS combinations allow some of this to be set in the BIOS under its power management functions. Other combinations may not have this flexibility.

As long as the machine is easily accessible the desired power results can be accomplished with little aggravation. However, the aggravation factor quickly increases with the degree of inaccessibility. It may even require a visit to a remote location just to push the power button after a power failure.

For years prior to the ATX style motherboards we at CPS have made products to remotely RESET equipment and/or control the AC power. The RJ I/O Cable Assembly was primarily used to Reset the equipment. It has a jumper that connects to the reset pins on the motherboard and provides a momentary closure. It is normally controlled through one of our Controllers (Telco or TCP/IP Network Controllers).

With the onset of the ATX boards we also started to connect the RJ I/O Cable Assemblies to the power button and were able to remotely push the power button, or even push it twice. We even added an additional four second push time command to some of our Controller's "extended reset commands". If more than four seconds were required, you could use one of our Relay Boxes. It would push the button until the next call was made, in effect "pushing it twice" (Telephone Line or Network Controller required).

Finally, rather than continuing to patch with the RJ I/O Cable Assembly, we developed the APB. It includes all of these patches, plus some. The APB fits inside the PC and connects to the power button (no card slot is required). In its basic configuration it will simply push the power button when power is restored after a power failure (no Controller required). It may not seem like much, but if your BIOS does not support the power ON function that you are trying to accomplish, it may save you a trip to a remote site or some extended down time when you can't get to a server at the moment.

Even if the BIOS does support the desired "resume power" function the APB may be preferred. It can delay the power resumption for up to 30 seconds to give the AC lines a chance to stabilize before the machine is powered ON.

The APB also has other optional features. The addressable version APB-I has "up stream" and "down stream" RJ-11 connectors so that up to 20 of them can be "daisy chained" and controlled through only one controller or even through the serial port of an adjacent machine.

The Heartbeat version (APB-H) connects to the reset pins and the serial port. It automatically performs the RESET or power cycle function when the machine hangs without the need for an external Controller. If the AC power recycling is used to reboot a machine, the basic "auto push" function may still be required if the BIOS or chip set does not support the desired power ON results.

A battery backup solution is another option. It is intended to actually prevent power loss problems. However, it doesn't address the machine's hanging conditions and it is another expensive piece of bulky equipment that may itself require additional attention and periodic battery replacement.

See REBOOTING PRODUCTS for Base Units and Controllers