ohhhhhhhh boy.... this could lead you down a road past hell...... i had that problem a couple months ago... june to be exact..... and i just fixed my computer 2 days ago..... one thing lead to another and ... well it don't matter... its not the cable or power supply. make sure to see that your motherboard is not touching the case... the only thing touching the motherboard should be the standoffs (the things levetating the motherboard from the case).... if its not touching the motherboard, take your hard drive out and look behind it... there should be a jumper on the far right hand side. atleast thats what it was for me. check your hard disk manual to make sure. once you've done that and it still flickers, pull out your ram and reboot the computer. it should beep after a few seconds of booting. if it beeps, the ram is good. if it doesn't beep, the ram is the problem and should be replaced. if tht didnt work. clear your cmos. remove the lithium batter located on the motherboard. use a flathead screwdriver and pop it out of its socket for about 20 seconds and put the batter back in... try all that stuff and tell me what happenned.... i don't feel like typing anymore.