i want to manufacture the cpu cabinets so plz send me the standard sizes.
First of all, there's more to it than just knowing the size of the motherboard. You need to get the motherboard hole standoff spacings correct, the expansion slot spacing correct, and the I/O panel size and spacing correct, else the board will not fit squarely in the case. You can look for published specs on this, but the ones I found are out of date and you may be better off in just measuring some common motherboards very carefully to find out these values.
Here are most of the common motherboard sizes, from smallest to largest (width x length)
1. Mini-ITX: 170 mm x 170 mm
2. Micro-ATX: 244 mm x 244 mm
3. ATX: 305 mm x 244 mm
4. SSI CEB: 305 mm x 267 mm
5. Extended ATX/SSI EEB: 305 mm x 330 mm
There are a lot of other sizes out there, but these are the most common.