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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  • ThelvynD - Monday, November 15, 2004 - link

    We've been getting in new HP 7100s here at my work center and they've been in the micro-BTX format. I don't any major problems with it so far. Pic below.

    http://www.picsplace.to/044712/HP-BTX.JPG
  • Nonsense - Monday, November 15, 2004 - link

    #36 - Thanks Purav.
    Can you tell me - is the PS blowing in or out, and is the CPU fan blowing in or out? I'm still trying to figure where all the air is comming from.
  • PuravSanghani - Monday, November 15, 2004 - link

    #34: If you look at the picture of the backside of the B300 on page 8 there are groups of holes above the VGA expansion slot as well as to the right between the expansion slot and the power supply. There are also holes lining the bottom of the case if you look closely. We were surprised ourselves to find how well passively cooling all of the components in a system would actually work. And from the pictures you can also see there aren't too many holes for a large amount of air to come in through!
  • PuravSanghani - Monday, November 15, 2004 - link

    #25: Actually, the front panel connectors *are* standardized and combined into one single plug. We mentioned this on page 8 of the article, "First Look: AOpen B300 BTX case cont'd", in the paragraph where we talk about the auxiliary module.
  • Nonsense - Monday, November 15, 2004 - link

    #28 - I don't understand the air flow.
    If the CPU fan is blowing out the front of the case, then the PS _must_ be blowing in.
    Blowing hot air into a case does not sound good. Is that how it works?

    If the PS is also blowing out, then you have a vacuum. I do not see any heat comming into the case from the PS, so it must be blowing out...?!

    Where is the air comming from that is cooling the graphics card? It looks like mostly dead air in that corner - there are only tiny grills on the back.
  • Sunbird - Monday, November 15, 2004 - link

    From last paragraph of article:

    "The ATX case used more space and ran louder."

    Space is not evil!, its a good thing for when your drop a small screw, or have hands that fit your 6'6" frame. And loudness can be adressed in other just as succesfull ways.

    "Don't forget that additional non-redundant fans increase the failure rate of a computer as well - more moving parts."

    And what if the single fan on the BTX sollution fails? That is really non-reduntant if you ask me, anyone agree?

  • Sunbird - Monday, November 15, 2004 - link

    #20, I agree, I have a Packard Bell P1 133MHz flat desktop case PC in my workshop and that is almost exactly the same design as this, except the stuff like the optical drive, hard drives and power supply was swapped from the right to the left side of the case, othewise its exactly the same. Glad to see some oldschool designs again, lol

    #27's idea is brilliant, they quickly implemented something like that with the cases and their front USB options, those LED and power button connector have been around much longer. What's taking them so long?
  • epiv - Monday, November 15, 2004 - link

  • skunkbuster - Monday, November 15, 2004 - link

    flash in the pants?
  • Zebo - Monday, November 15, 2004 - link

    This is going nowhere quick. It's obvious Intel will no longer need it when they make the Dothan desktop transition plus AMD all case and PS manufactures hate the idea. Just wahtever you do don't go buying an $300 Lian Li and $120 PSU since BTX is a flash in the pants.

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