X-bit labs

Foxconn E-bot Small Form-Factor System Review (page 7)

Category: Mobile

by Platon Scheblykin

[ 05/03/2005 | 10:37 PM ]

Mainboard PCB Design

The mainboard the E-bot is based upon seems to be an integral part of the whole concept of this barebone, so we’re going to discuss it as such.

Mainboards for barebones are usually standard, incorporating general engineering solutions, typical forms and sizes, but it’s different with Foxconn’s creation. Just take a look at the outline – do you often see mainboards with a corner cut off? This was done for the mainboard to fit into the case, as we said above. The hottest components, i.e. the processor, memory and North Bridge, are moved as far away from other components as the small PCB area permits, for better airflows. This placement isn’t perfect, though. The memory slots are near the front panel of the case, and the airflow from the bottom to the real panel of the case is passing some distance away from them, leaving the memory unattended.

Another minor drawback is that in the assembled system the fastening bracket of the CPU heatsink hangs somewhat above the North Bridge’s fan, thus hindering airflow. It’s even worse with the CPU voltage regulator elements that are placed under the CPU heatsink, which protrudes far off the CPU socket. The fan doesn’t fit too firmly to the heatsink and creates some airflow around the regulator’s elements, but that’s not enough. Moreover, the heat pipes stretching from the cooler’s sole go right above them.

In brief, the elements of all the three power channels are scorching hot at work. All the connectors found at the barebone’s back panel are located below the heatsink. We’ve already discussed them in the beginning of the article.

The elements that don’t dissipate much heat, and all the connectors and expansion slots too, are grouped at the bottom part of the mainboard’s PCB. Two connections seem to be located properly: the IDE cable and the power cables of the hard drive and the optical drive. The IDE connector is located near the devices that attach to it. The IDE cable folded at a 90-degree angle lies on the optical drive and takes almost no space inside the case.

As for the power cord, it’s small and doesn’t occupy much space in the case. Since the E-bot uses an external power source, the IDE devices are powered by a Molex “male” connector a cord with three Molex “female” connectors is attached to. All the power cables are color-coded according to the ATX standard. The rest of the connectors are located rather inconveniently, since their cables either stretch through the entire case or create such a mess that it becomes difficult to access the mainboard. For example, you can only handle the Clear CMOS jumper with tweezers and a flashlight.

The PCI expansion slot is placed in such a way that the nearby cables will lie on the installed card, which is undesirable.