At the beginning of 2007 AMD unexpectedly announced the intention to develop a new, open motherboard and chassis form factor, entitled DTX (because CTX was a monitor company?).

The idea behind DTX was to finally standardize small form factors for use by white box PC builders and the enthusiast community, both areas where BTX has not been able to really penetrate.

While Intel's BTX spec has been well implemented by the major OEMs, a quick search on Newegg reveals ATX/BTX compliant towers and two motherboards, both from Intel. We simply don't build BTX systems, which is unfortunate because it means that there's no real standardization in use for small form factor PCs by enthusiasts.

AMD also views BTX as too large of a departure from ATX for motherboard and chassis makers to justify bringing BTX boards to the enthusiast community. In AMD's eyes, BTX was a solution for a problem that no longer exists: the power-hungry Pentium 4. Thus DTX was designed as an auxiliary form factor standard, fulfilling the need for a small form factor standard that'll actually be used by more than OEMs.

What is DTX?

In February 2007 AMD published the DTX spec, the 10 page mechanical interface specification is unusually small for a brand new form factor, but it quickly makes sense when you realize that much of DTX is built off of ATX.

The DTX spec has four major requirements:

1) Motherboard size
2) Mounting hole locations
3) Rear I/O dimensions/locations
4) Expansion slot connector locations

There are two DTX form factors outlined in the spec: DTX and mini-DTX, both designed to augment, not replace, ATX.

DTX motherboards will measure 9.60" x 8.00" (243.84 mm x 203.20 mm), while mini-DTX boards measure 6.70" x 8.00" (170.18 mm x 203.20 mm). Mini-ITX motherboards can also be used in DTX compliant cases.

The big selling point for DTX is that it uses ATX mounting hole locations, so DTX motherboards can be used in current ATX cases.

DTX motherboards can have a maximum of two slots, either PCI Express or regular PCI can be used. The I/O connector plane is identical to what's used in current ATX motherboards, although the layout can obviously differ from board to board. The DTX spec doesn't govern what type of ports must be used, leaving it up to the motherboard makers' discretion.

There are no new power supply requirements for DTX, it simply requires the same 24-pin power connector and 2x2 +12V connectors supported by the current ATX specification. Cooling requirements remain unchanged as well, DTX systems can use standard heatsink/fan units.

All in all, the DTX spec is really about motherboard size, thus we've got a very simple spec to deal with. It truly is an augmentation to ATX rather than a replacement.

Differences between BTX and DTX
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  • leexgx - Monday, October 22, 2007 - link

    monitors with DTX Clamps to Hold the PC to the back of the monitor :)

  • Bluestealth - Monday, October 22, 2007 - link

    Or a standardized docking slot for mini-desktops for monitors.
    Although the clamps allow for more varied case designs.
  • AmberClad - Monday, October 22, 2007 - link

    I really can't see myself using this form factor. I use mATX right now, and that has a good balance of compact size and expandability -- enough expansion slots to meet an average user's needs without having an excess of empty slots like with regular ATX. If I wanted to go really small, I'd pick mini-ITX. I look at this DTX design, and I see something that is neither as flexible as mATX, nor as compact as mini-ITX. Building a decent HTPC with a motherboard that only supports two slots may prove difficult -- you'd have to compromise between picking a video card, TV tuner, and sound card. So DTX doesn't seem all that interesting for DIY use.

    On the other hand, it might be quite suitable for small form factor OEM systems. But with Apple's partnership with Intel these days, that's one system builder that probably won't be using this form factor...
  • Ajax9000 - Monday, October 22, 2007 - link


    Building a decent HTPC with a motherboard that only supports two slots may prove difficult -- you'd have to compromise between picking a video card, TV tuner, and sound card.

    Foregoing the soundcard and using a digital audio connection to proper receiver/amplifier would be my choice.

    I've been looking at mini-ITX but getting even a video card and a TV tuner (i.e. not USB) plugged in is difficult without resorting to exotic internal cabling/whatever.

    So, I'd like a mini-DTX ... but supporting C2D thanks, the AMD processors don't excite me just at the moment ...

    Shuttle is supposedly going to re-enter the motherboard market with boards such as the FP35 and FX38, but they are BTX-style.
  • yyrkoon - Monday, October 22, 2007 - link

    DTX in my opinion has nothing to do with BTX, and has more in common with mini/micro-ITX.

    Ok sure, it is so far non widely accepted, like BTX, but that is where the commonalities stop.

    Anyhow, it would be good to have something similar to mITX, and something that is standardized, and hopefully, not a rip-off fest waiting to happen(like mITX . . .).
  • defter - Monday, October 22, 2007 - link

    So if you add a video card and a sound card, you will have zero slots left...

    It's unlikely that DTX will replace ATX among those who build PCs themselves, because of this slot limit. For example with micro-ATX you can have 4 expansion slots.
  • sprockkets - Tuesday, October 23, 2007 - link

    yeah, but how many have you seen upgrade their video card? And if you need to replace the ethernet card, there is always usb.

    Think business stations as well. Oh wait, they are going back to diskless computer terminals.
  • Regs - Monday, October 22, 2007 - link

    I think ATX is reaching its limits too. The size of a video card just keeps getting bigger and bigger..
  • kyp275 - Monday, October 22, 2007 - link

    I see this as mostly for the HTPC crowd than anything else, where you don't really need much as far as expansion slot goes.
  • BansheeX - Monday, October 22, 2007 - link

    One of the things that always confuses me is that today's PCs seem unnecessarily large and we could easily reduce material waste and power consumption by ditching ATX completely and making micro-atx/dtx/whatever the new standard. It seems logical that the desktop should move from 3.5 HDs to 2.5 HDs, 5.25 CD Drives to Slim CD drives, and full profile graphics/sound cards to low-profile graphics sound cards. At one point, I'm sure it wasn't technologically attractive, but these days even 2.5 hard drives can reach extremely high speeds and capacities. The price premium is largely a result of it NOT being the standard, so that would not be an issue. Floppies are gone or USB-alized, so that's not taking up space anymore.

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