BTX Cooling and Airflow Explained

We know the purpose of the BTX design and why each component is placed where it is, but the question is, will it work? Will a single CPU heatsink fan be able to effectively cool all of the critical components in a system? In our preview of BTX last year we explained the placement of each component as well as showed a top view of the heat paths in a BTX system. The CPU, Northbridge, Southbridge, and VGA card are all inline which creates a single path for air to flow and in one single direction, from front to back through the thermal module.


From the picture we see the flow of air pushed back through the CPU thermal module towards the Northbridge, Southbridge, and VGA card. As this air flows around the CPU, it warms up, as we can see from the red areas to the left and right of the CPU. This warm air then flows over the Northbridge and seems to cool as it travels further back in the chassis. At the left we see the channel of air flowing to the left over the memory and out through the PSU. The channel on the right flows straight back to the VGA card and out through groups of holes in the back of the case.

Intel will incorporate various other features that will help their CPUs perform at an efficient level no matter the conditions beginning with the Pentium 4 6xx series chips scheduled for Q1 of 2005. One feature is an enhanced version of their mobile processor SpeedStep technology called just that, Enhanced SpeedStep Technology; EIST or EST. EIST will allow the operating system to lower the CPU's power state during idleness which will reduce heat dissipation and power consumption. Another feature which will have a great effect on a system's thermal conditions as well as safety is the Thermal Management feature. This feature allows the CPU to immediately cut its clock speed to a fraction of its normal operating clock speed when the motherboard detects it is operating at temperatures out of the norm.  There are a lot of Centrino-eque technologies at work here.  The lessons learned from Pentium M have played heavily on system design as well as processor design. 

So how will Intel's new BTX form factor affect third party manufacturers specializing in cooling equipment? The fact of the matter is that cooling hardware will always be required. We have seen in past ATX case reviews that no matter how many fans are in a case, a single 80mm fan at the front as an intake, or a set of six 80mm fans throughout a mid tower case, current hardware will operate under normal loads. Users, however, still prefer to spend their money on extra cooling equipment to get the most out of their systems. Intel has been bundling their heatsink fans with their CPU's since the beginning while third party manufacturers like Zalman and Thermaltake provide solutions for enthusiasts who prefer custom hardware. So the market for third part hardware will still be there for the BTX form factor as it has been for ATX.

BTX Cooling and Airflow First Look: AOpen B300 microBTX case
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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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