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.
Facebook
Twitter
RSS
77 Comments
View All Comments
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.