empacher, which test pattern are you talking about? As for cooked bits and pieces, mobos have a series of beeps they give out depending on what isn't working properly, ram, gfx card etc etc etc. This doesnt rule out everything but I put it to you that its either a) a psu snag (possible, do you have it surge protected? easily tested if you have another pc/psu to hand...) or b) a cooked mobo (harder to test, unless you have two pcs with roughly the same config...)
But in the past I have known a psu providing insufficient power to cause a similar problem (ie enough to start the mechanics but not set the numbers crunching).... seems unlikely if they're producing the correct voltages as you say, so most likely the mobo... get yourself a shiny new pc my man/woman!