Intel's Long Awaited BTX Form Factor
by Purav Sanghani on November 15, 2004 5:31 AM EST- Posted in
- Cases/Cooling/PSUs
Examining ATX
The ATX form factor was designed by Intel back in 1995 to improve on the AT form factor. It brought about changes that would help standardize placements with various types of hardware, one being full length expansion cards; in original AT layouts the processor sockets were positioned at the front of the motherboard which kept full length expansion cards from being used. Now that the ATX form moved the CPU sockets to the back right corner of the motherboard full length PCI/ISA cards had plenty of room.AT also had the problem with drive bay interference since the AT motherboards were longer from front to back. With ATX the motherboard is cut wider, instead, to provide some clearance between drive bays and the board itself. Moving the CPU socket also aided in this change since there was a need for board space at the back right instead of the front left corner of the motherboard.
Some of the other changes from AT to ATX:
- Power supply connection AT motherboards used dual 6-pin connectors to power the system which was confusing and also potentially dangerous if we did not know what went where. The ATX specification implements a single 20-pin connection from the power supply to motherboard to eliminate confusion and damage to hardware.
- Power management The older AT specification also had the power button of the case hard wired directly to the power supply. The ATX specification implements the "Soft Power" feature which allows the motherboard to turn the power supply on and off by software. For example, when shutting down the Windows OS in an AT set up the system needed to be manually shut down by pressing the power button. The ATX form factor allowed the system to be automatically powered down after the OS logged off.
- Integrated I/O, peripheral connections On older AT boards, instead of having the parallel and COM ports we see at the back of the motherboards, extra cables were required to extend those features to the case. We needed to run cables from pin headers on the motherboards and mount them to the cases to be able to connect printers or other devices that used these ports. When the ATX form factor was introduced, these connectors were soldered directly on to the motherboard to both reduce the time to install components and the overall cost of a system, as well as to increase the reliability of the ports.
- Cooling and air flow Moving the CPU to the back right of the case closer to the power supply and the backside fans had a positive effect on cooling. Warm air created by the CPU would be pulled out through the back of the case as well as up through the power supply if it had a fan facing the CPU.
The ATX had a clear goal in mind; a new design that would reduce clutter, standardize component design and bring more control to the motherboard. The BTX mandate is a little less clear; reduce the PC footprint while more efficiently cooling the components. Keep this mandate in mind as it plays heavily on our conclusion.
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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.