Intel had a new revision of the ATX spec made for the Pentium 4 to cover its various physical needs. The ATX 2.03 specification covers the new case, motherboard, and power supply designs needed to be compliant with Intel's reference Pentium 4 platform design. This will have a direct impact on you if you ever plan on purchasing a Pentium 4 system, so we suggest you read this section and what we think the consequences will be. This will have less of an effect on companies like Dell, IBM, and Compaq, who tend to design their own platforms off of what Intel designs.
On the case side, ATX 2.03 specifies four new screw holes on the motherboard tray. These screw holes are needed to mount four screw-in supports that lie under the Pentium 4 processor. These four supports are to hold up the reference Pentium 4 heat sink, which we will talk more about later in the article. There are no cases we know of available today that meet the ATX 2.03 specifications, so we suggest you hold off on buying that $200 super cooling case if you think you might ever get a Pentium 4. Don't fret though, we do expect that you will be able to manually drill the four holes into an old case in order to mount a Pentium 4 without having to buy a whole new case.
On the motherboard side, ATX 2.03 defines a new keep away zone over the motherboard. This gives space for motherboard components and heat sinks, space that won't be infringed upon by CD-ROM drives or power supplies if a case is to be ATX 2.03 compliant.