ATX or Micro ATX?

[Noels]

Hi Noels Here,
I am bit confused about the different sizes of cabinet. i have a Compaq PC purchased last year only.Recently PSU broke down and it has 200wt supply but while purchasing new one i thought go for higher PSU (hmm maybe 300-350 watt) but the Tech support guys on the tell me that i could not opt for a 300-350 watt as my PC has Micro-ATX. i don't know what is all this pls help?

[Vigour]

ATX

A full size ATX board is 305mm wide by 244mm deep (12" x 9.6" ). This allows many ATX form factor chassis to accept microATX boards as well.

microATX

microATX comes with a maximum size of 9.6 inches x 9.6 inches (244 mm x 244 mm), but some microATX boards can be as small as 6.75 inches by 6.75 inches (171.45 mm x 171.45 mm). The standard ATX size is 25% longer, at 305 mm × 244 mm (12" wide x 9.6" deep).Currently available microATX motherboards support CPUs from VIA, Intel or AMD.