hi, one of our custom-built computers died (the power supply went & it took the mobo with it), so we bought a new one (WinFast K7S741GXMG). i put it in, powered up, and entered setup. as i started to change the date, it locked up. so i restarted it and now i get nothing. no screen, no beep. i took the memory out & put it back in but that didn't help. also, the power supply is brand new and so is the memory (Kingston 512MB DDR PC2100).