I am building a new machine right now. The mobo is an ASUS A8N-SLI deluxe, AMD 64 3500+, ATI Radeon X800XL (PCI-E), SATA Raptor, two IDE HD's and RAIDMAX 420W Case. I've built many systems and work as a network manager for a large school district. I put the machine together with no issues, boot it up and it posted fine (this mobo talks for post instead of beeps, very cool) as soon as I moved the machine upright and plugged it in, no post! as soon as I lay the machine on its side it post just fine....I got the first mobo replaced and just got a new one and it has the same problem. I put Artic Silver between the chip and heatsink (its a retail chip with the stock heatsink) Anyone out there had a similar problem and have any ideas? I really don't want to run such and expensive machine on it's side forever.