BTX Cooling and Airflow

Again, the main reasoning behind Intel during the redesign of the ATX form factor was to design a more efficient cooling solution. As components are built faster they also run hotter. The ATX form factor improved on the AT specifications by placing the CPU closer to the back of the case where fans could be mounted as exhausts to pull hot air from the CPU out of the chassis and away from other components. Now that those other components in PCs are beginning to expand in performance and functionality they are running at temperatures as high as that of CPUs so a new design needed to be devised to help cool these components in a more efficient manner than just slapping more fans in a standard case.  Now, we have come full circle with the CPU moving back towards the front of the case.  Since Intel has the standards on PCIe very heavily controlled, worrying about PCIe cards extending too far to the front of the case should not be a problem. 

Intel implements a more efficient passive cooling system by placing the majority of components inline with the CPU towards the rear of the chasis.


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The most important piece of hardware when it comes to cooling is the CPU heat sink fan. Without this a CPU would not POST, and would most likely damage the hardware. Intel has included what it calls a "BTX Thermal Module" which consist of either a spiral or stacked-fin heatsink and a fan which is mounted at the end of a plastic duct, facing the front end of the case. Intel has not limited this hardware to only one type though. In their virtual press kit Intel speaks of Type I (Standard height) and Type II (Low profile) thermal modules. The Type I module will be designed for a broader range of cases from small form factor to the larger full tower applications while the Type II module will be designed specifically for the ultra-small form factor designs.


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Intel also mentioned that along with those two types of thermal modules there will be variations in the units for processors rated at different Thermal Design Power, or TDP levels. The difference in modules will exist mainly with the heatsink, with slight variations in the duct. The fan will, however, remain the same within the same type (Type I/Type II) of module.

This thermal module was the only piece of cooling hardware aside from the power supply which we found to be surprising. We couldn't imagine running an ATX case with only one CPU heatsink fan and we have our doubts about Intel's single module design, but we will leave that to our benchmarks to decide.

Examining BTX cont'd BTX Cooling and Airflow Explained
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  • sprockkets - Monday, November 15, 2004 - link

    Not at all 48#.
    The move from AT to ATX, wonderful, nice, a big improvement.

    ATX to BTX, err, why?

    Well, I do see a need to have this in place with LOW PROFILE cases. Otherwise, the ventilation is terrible. And pBTX looks nice too. BUT, all you are doing is standardizing the design of small case designs, something that those poor OEMs had to do (aww, poor dell doesn't have to design utterly poor cooling solutions, like the ones we have at work, where the case doesn't even have front air intake, and the processor gets cooled from the very air it exhausts, sad). Large cases such as ATX do not need this.

    Hmmm, doesn't that L shaped power supply bring back GREAT memories?

    Add to it, why didn't video cards get mounted with the cooling on top? That would have helped it a lot with cooling.

    For that matter, you people REALLY need to get with the program with InWin cases. Their latest uATX case has a large fan duct for processor fan intake, a large holed opening on the bottom left hand corner for cooling the add in cards, a quiet 90mm fan exhaust and a 120mm fan on the 300w power supply for exhaust.
  • Bozo Galora - Monday, November 15, 2004 - link

    Intel quicksand gets deeper
  • DS Delaroca - Monday, November 15, 2004 - link

    so the way i see it, its that for a long period of time we will have to standards for each company, BTX for Intel ATX for AMD, so these means for us DIY computers builders the future its limited by what CPU U choose,as for none of the parts for an AMD system would be not interchangeble with an INTEL BTX system, as it is today that both use the same ATX desing, and i mean u would not be able to use the same PS, video card,sound card and any non BTX complyant part, correct me if im wrong if this correct THANKS.
  • pjarvi - Monday, November 15, 2004 - link

    Unless I misread the article, the exhaust is blowing out the front?!? If that's true, then that's really, really, stupid. Every company I've worked for buys dekstop systems, that sit infront of, or to the side, of employess. If BTX is blowing exhaust out the front, then a lot of people are gonna get cranky due to allergies. I know that I personally can't stand a fan blowing air in my face, and hot dusty air is gonna be a million times worse.
  • Nonsense - Monday, November 15, 2004 - link

    The airflow described on page 6 is inconsistent:

    "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 back to front through the thermal module"
    ...PICTURE...
    "From the picture we see the flow of warm air pulled forward from beyond the VGA card. As it moves towards the front of the case the air flows over the Southbridge and Northbridge passively cooling each chip. "

    Now look follow the link at the top of that page: "heat paths in a BTX system" which goes to: http://www.anandtech.com/casecooling/showdoc.aspx?...

    Which says: "The redesign of the board layout was done in order to improve airflow through the system; moving the CPU to the "front" of the case allows it to be right next to the intake fan, giving it the coolest air out of any component in the system. You will then notice that the chipset is directly in line with the CPU, allowing airflow over the CPU's heatsink to be channeled over those heatsinks as well before exiting the case."

    These two articles directly contradict of each other. I think the latter is correct. Please post a correction, thank you.
  • PsharkJF - Monday, November 15, 2004 - link

    Fat fingers for ATX ;]
  • Chuckles - Monday, November 15, 2004 - link

    OK, so after all that, I have only one question. Why in the name of $DIETY are they venting out the front of the case? Do they want the dust bunnies to have a home? Why not flip the components around and (with a little coercion towards the graphics card manufacturers) vent all the hot air out the back?

    Also, to those that think AMD is immune to the heat problems: Power consumption (and dissipation) has gone nowhere but up in computers. Heck, ten years ago CPU's didn't have a heatsink, much less one with a fan. With increased heat has come to be expected more noise. I personally think BTX is a stumble in the right direction towards reducing the noise while dealing with the heat output of modern and future micorprocessors.
  • ZobarStyl - Monday, November 15, 2004 - link

    Yeah 48, what about the guy who's pissed cuz he can't do a P4 to P4 upgrade because the damn thing is now obsolete for the mobo AND Case/PSU? And all the HP/Compaq old school jokes are true; this looks exactly the same, and will have all the same problems.

    The issue isn't so much that we hate Intel, it's that they are a) forcing this on us and b) it has little tangible benefits to necessitate the cost and some of c) AMD chips may not be able to use the standard, but have no need for it anyway. Mostly, we're all tired of Intel moving the industry around wherever and whenever it wants to make up for its own downfalls.
  • bob661 - Monday, November 15, 2004 - link

    #48

    No one needs it but Intel. It doesn't take a "fanboy" to see that. AMD does NOT have the heat issues that Intel does. That's just a fact. There are some here that hate Intel but some do not. I will only buy what gives me the most bang for my buck. Intel does not provide this at the moment. So I will continue to buy AMD unless that changes. There are others here with the same mentality. No hating involved.
  • five40 - Monday, November 15, 2004 - link

    I'm not a fan boy of intel or amd but so much blatant dislike of intel is sad. It seems that if AMD came up with this standard you guys would be saying how amazing it is and that you want it ASAP. Since it's Intel, no one "needs" it.

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