Computer shuts off. detail descript.

ok. im haveing problems. i have a P4 1.8, 756 mbit ram, nividia 7200 pci, and some matsonic ms-i17+(usb) board.

i installed vista on friday and my computer kept shuting off. i figed that vista was useing to much cpu and over heating it. then on sunday i got fed up of it shuting off so i tryed to reinstal xp but i had the upgrade disk's so i couldent even use it it said cant doengrade. fin so i took my HD out and formated it on my sis computer. i tryed to reinstall it with the right disks i got from my frined it keps saying no hd conected. so i messed with the jumpers and it started to install it. but it kept shuting off wile instaling . like it looked like it went into sleep mode. so i had to keep restarting the comp wile it was instaling then it finnaly installed and i loged on. but kept shuting off. so i RE installed it with my upgrade disks since i hade a previous version of windows the instalation went great. except some times the screen just went heptic like weird colored lines out of no wheres. and wile instaling once i have guages that lite up blue in the front and they flickered. ithought maybe my gfx card so i updated the drivers still no good. help. i know the cpu dosent over heat i put a huge fan blowing in it and it still shuted off. help!!

What version of Windows Vista are you using?

i went back to xp sp2, i did some more testing today and i come to belive its my mother board. im acualy not really worried i just ordered on sat a new mother board and pros.