Examining BTX cont'd

The D915GMH is essentially a microBTX version of our D915GUX motherboard with a few functional differences on top of the obvious BTX design. When we first laid eyes on the D915GMH the first thing we noticed was the arrangement of the CPU socket, Northbridge, and Southbridge. The CPU socket is placed at the front of the motherboard with the Northbridge behind it slightly to the left and the Southbridge behind the Northbridge directly in line with the CPU socket. Each is positioned on a diagonal which we assume will improve air flow around all three chips. Since these components are three of the hottest running components in a PC it made sense to position them in line from front to back and we expect fans to be placed in that same linear arrangement.

A design that revolves so much around irregularly placed components was slightly unusual for us to see.  Although software dictates the exact routing of all the traces from component to component, its very obvious that some very complicated math went into assuring each bridge and component was placed correctly.  The fact that almost nothing seems to be at a right angle is a little overwhelming at first.

The IDE and Floppy ribbon headers were separated on the board. We found this to be inefficient, especially for the floppy drive, since they are on opposite sides of the system. Though not as important nowadays since SATA drives are moving into mainstream PCs, those who would like to use floppy drives are left with only the option of using a lengthy rounded cable. Since the AOpen/Intel combination we received today looks more like an OEM design than something we would typically buy and assemble from NewEgg, problems with the floppy cable placement shouldn't be a huge issue.  


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There are 4 DDR memory sockets which are placed at the far left edge of the board. Keep in mind our D915GMH runs on DDR2, but other than design layout that is the only major difference between our microATX and microBTX motherboards.


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The PCIe x16 slot is positioned about 3 inches from the rightmost edge of the D915GMH. Since the AOpen B300 is a half height case a riser card is included for the PCIe x16 slot. This allows the VGA card to be mounted towards the center of the motherboard to keep it inline with the CPU and chipset.

Examining BTX BTX Cooling and Airflow
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  • stephenbrooks - Monday, November 15, 2004 - link

    Do you think if you connect the power to the fans the other way around you can get air to flow in from the front and come out of the back instead?
  • SolarWind - Monday, November 15, 2004 - link

    Actually, I like how they moved the processor towards the front of the case. This way the processor isn't in the path of hot air rising from the video card.

    Also, having the video card flipped over means that high performance heat sinks on the video card won't block a PCI/PCI Express slot.
  • DeeTees - Monday, November 15, 2004 - link

    Your right, I would have sworn that I saw that mess inside of a Packard-Bell. At least they have not yet started using custom fasteners that you need a special tool to replace or upgrade components. (?)
  • quanta - Monday, November 15, 2004 - link

    BTX may deliver overall cooler temperature per volume of space, but what about all the hot air that was used to cool the CPU? Wouldn't the hot exhaust cook the video card and bridge controller, limiting overclocking potentials? Temperature aside, having air intake in front of the case reduces usable drive spaces that would be used for fan controllers. If I were designing BTX, I would put CPU on top corner, and a curved 'casing' that would route exhaust to top blowhole.
  • PuravSanghani - Monday, November 15, 2004 - link

    #42: Actually it us just these micrBTX cases that do not have rear exhausts...so far. We may see case manufacturers employing case fans as soon as BTX becomes a mainstream form factor.

    At Computex this past year, we did see some companies like Enlight (http://www.anandtech.com/casecooling/showdoc.aspx?... show off some mid tower cases which did have room to add extra case fans. We still have a lot to look forward to concerning the new form factor.
  • skunkbuster - Monday, November 15, 2004 - link

    it would have been nice to have a rear exhaust...
  • bob661 - Monday, November 15, 2004 - link

    Man those P4's sure do run hot. 63C WITH the BTX case. My A64 runs at 36C inside the ancient ATX case. I'm still running the OEM CPU cooler and oh about 6 case fans. :-)
  • Cygni - Monday, November 15, 2004 - link

    Looks like BTX is going to work out for Dell and HP... but I dont think its going to have much effect for the enthusiast and self built markets. Seems to me that its going to be at its best in mBTX situations, but full BTX seems ho-hum. I guess its just more crap i gotta buy next time i upgrade. BTX mobo, BTX case, DDR2, SATA HD, PCI-Ex video card, new CPU... they really havent left anything for me to KEEP during a P4 to P4 upgrade. Me no likey.
  • vedin - Monday, November 15, 2004 - link

    Where am I supposed to put a window and neon light in that case? Hmm?
  • Spinne - Monday, November 15, 2004 - link

    I don't see what the problem is with BTX cases. The design layout, atleast for Intel processors makes a lot of sense as far as thermal regulation goes. Channeled airflow on ATX cases is a niche market, and the fact that there are no standards means that you can't be assured of compatibilty across motherboard solutions. You really don't want to have spent money on a new mobo and case only to find that a lousy capacitor prevents you from using channeled airflow. Also, there's no reason why a manufacturer can't place additional fans in a BTX case to cool the case further. Remember, cases are not upgraded as regularly as the actual hardware, so one always has the option of moving to BTX at one's lesuire. I dunno about you guys, but I live in a college dorm, and the smaller my case footprint is, the happier I am, especially if it's a full form-factor case.

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