CLASS 1 - Xtreme class.
Anything goes in this class, any CPU, any cooling, any mods.
CLASS 2 - Socket A under 2.3gig.
Any Socket A CPU running under 2.3ghz, any modifications to graphics card (bar memory chip swap), any cooling.
CLASS 3 - Pentium 4 under 2.8gig
Any Pentium4 processor (not EE) running under 2.8ghz, any modifications to graphics card (bar memory chip swap), any cooling.
Class 4 - SocketA Aircooled.
Any Socket A CPU running under 2.3ghz, any modifications to graphics card (bar memory chip swap), AIR cooling only.
Class 5 - Pentium4 Aircooled
Any Pentium4 processor (not EE) running under 2.8ghz, any modifications to graphics card (bar memory chip swap), AIR cooling only.
Class 6 SocketA Watercooled.
Any Socket A CPU that is Water/Air cooled, any modifications to graphics card (bar memory chip swap), Water cooling only on graphics card.
Class 7 Pentium 4 Watercooled.
Any Pentium4 processor (not EE) that is Water/Air cooled, any modifications to graphics card (bar memory chip swap), Water cooling only on graphics card.
Class 8 AMD A64/FX/Opteron/P4 EE
Any AMD A64/FX/Opteron or Pentium4 EE processor at any overclock and any cooling. Any modifications to graphics card (bar memory chip swap) Any cooling on the graphics card.