Sometimes my computer takes up to 5 minutes to post. Other times it boots right up from being completely powered down. I've tried unplugging all the drives so it was just the PSU, MB, RAM, and video card. It still didn't post. I'm thinking it's either the video card or the motherboard. The computer will boot up right away on a restart or if it's been running for a while and shut down for 30 seconds. The computer is brand new and already had the video card repaired once and one dimm replaced. It's an AMD Athlon 2500 Barton core, AGI 300 Watt PSU, 512 MB Dual channel (2x256), 200 GB HD, 16X DVD, 52x32x52 CDRW, Radeon 9500 Pro 128 MB, and Windows XP. Any ideas on what it may be and how to test it without having a spare computer or AGP video card? ATI thinks it's the power supply, the computer manufacturer thinks it's the video card or motherboard.