I have been building systems for over 10 years and this problem has me totally perplexed. Any help from you hardware gurus's out there would be greatly appreaciated. Here's a list of the hardware and a history of what happened to the system I am trying fix. Original Hardware: Asus A7n8x Mobo, Athlon 2500+ CPU, 250MB PC2100 RAM, GEForce MX 4000 video w/128MB, 80 GB W. Digital HDD, NEC DVD Writer and 54x CDROM. Last week I added 1GB of PC2700 RAM, and a 200GB Maxtor HDD. I also replaced the CD ROM drive with DVD ROM drive. I added components 1 at a time so it would be easier to identify any problems. Anyway I successfully installed all HW and everything was rocognized and working fine. I partitioned the new HDD and did a quick format on it, browsed the web a bit and checked to see if the DVD ROM drive could read a disk(it could). At this point the system was working as it should. I then proceeded to copy my FTP site to the new HDD(about 35GB). It copied for about 4 or 5 minutes and the system shut off. Attempts to power it back up failed. I have another ATX case so I took the Power supply out of it and put it in the system in question. With this P/S the HDD's would spin up for a few seconds and then quit. Obviously the 1st P/S was dead. Since I was planning to build another system anyway I went ahead an ordered a New MoBo,CPU,256MB PC2700 RAM and P/S. I thought that the Board or CPU or possibly the RAM could be fried. Today I got the new MoBo, P/S, RAM and Athlon XP 2600+ CPU and replaced the old board, CPU and P/S. I am still getting the same thing- HDD's spin up for a few secs and then nothing. Here's where I am now. New CPU, MB, P/S & RAM. I am still using the same HDD's and Video. However I have even tried to boot this system with an old old PCI video card and just a floppy and still nothing. I don't think the drives are bad because I put them in an old pentium system I had in the closet and they would spin up and continue to run. The old P5 system tried to detect them but its BIOS is so old that it can't handle disks that large. In any case I should be able to get into the BIOS setup with just a floppy and video? Anyone have any idea what is going on here? I am about at my wits end.