The most recent ATX PSU standard is version 2.31 of mid-2008. The standard ATX form factor dimensions are 140(D) x 150(W) x 86(H)mm. However, there are various other form factor sizes such as:
SFX – 100(D) x 125(W) x 64(H)mm
TFX – 175(D) x 85(W) x 66(H)mm
PS3 – 100(D) x 150(W) x 86(H)mm
FSP offers solutions for all these form factors and more.