When I started to notice this problem I had made no changes to my PC. Lately my PC will not boot up in the morning on first try. I hear post beep, one short beep, then I see the XP Home screen with the blue dial showing the OS is loading and after 10 sec, the screen goes black and the CPUlight shows green. On second boot everything starts up fine. Also if the PC has been on I can turn it off for a hour and it will still start up fine. There are no error messages in the computer management event viewer. No unusual sounds or smells. I used the hard drive’s manufacturers diagnostic testing. I ran all tests and no errors. I reseated my RAM. I used MEMTEST and the RAM is fine. I reseated my video card and reloaded drivers. Then I tried a new video card which met MOBO specs. I have reset the bios to known working configuration for good measure. My PSU is about a year old. I did check the number of amps on the +12v rail, etc. I reconnected all the power connectors tightly. Then I installed a new and more powerful PSU for good measure. The PC is still doing the same thing as I mentioned earlier: “will not boot up in the morning on first try. I hear post beep, one short beep, then I see the XP Home screen with the blue dial showing the OS is loading and after 10 sec, the screen goes black and the CPUlight shows green.” This PC has run flawlessly for years. What could be causing this PC not to boot when PC is cold?

Board flex, lan or via or legs popping or hard drive going out would be a guess. If you think the temp is the issue then test it. Warm the computer (safely) and see if it is that. I read it wrong and answer it wrong too. So get off my case you peanut.

try downloading "seatools" off the seagate website, and run that. It will test your hdd for bad sectors. I would think that it was a software related issue for the fact that it restarts when loading windows startup, and usually this sort of issue is caused by a faulty hdd. Have you tried starting windows in SAFE mode? this will help determin if it a piece of software that is trying to load up that is causeing the reboot.

Update your video card drivers. If you are already using the latest, try going back to an older version. "Lately my PC will not boot up in the morning on first try. I hear post beep, one short beep, then I see the XP Home screen with the blue dial showing the OS is loading and after 10 sec, the screen goes black and the CPUlight shows green." It sounds to me like Windows is, in fact, running, but you have no video. The video card drivers load with Windows (but not in safe mode, which uses VGA mode video). A faulty driver/card can cause the symptoms you describe. "Have you tried starting windows in SAFE mode? this will help determin if it a piece of software that is trying to load up that is causeing the reboot." For the record, drivers are software. Please let us know if you found someone's advice to be helpful.

"On second boot everything starts up fine. Also if the PC has been on I can turn it off for a hour and it will still start up fine." Correct me if I'm wrong, but if the video drivers were corrupt/not working properly, wouldn't it not display at all, regardless of how many times the computer was restarted/ turned off/on? "For the record, drivers are software." I never said that they weren't.

"Correct me if I'm wrong, but if the video drivers were corrupt/not working properly, wouldn't it not display at all, regardless of how many times the computer was restarted/ turned off/on?" Not necessarily. A corrupt driver can work perfectly sometimes, but not at other times. I've seen intermittent problems with drivers many times (very hard to pinpoint, being intermittent). "I never said that they weren't." I never suggested you did. I was merely pointing out to the OP that "software" includes drivers (not just programs). Please let us know if you found someone's advice to be helpful.

Since the OP tried 2 different video cards (which if they were 2 different models use 2 different drivers), I don't think the problem is the video card/drivers. As jefro pointed out, it could be the hard drive failing. IMO, I think your hard disk is failing due to a bad connection with the hard disk circuitry, or with the actual disk. When your computer is warming up, it causes the circuitry or disk to expand and therefore opens the connection and causes your PC to work fine the second time you restart it. As response 2 says, download SeaTools and test with it, particularly at a time when your computer is cold and you haven't turned it on in several hours. Most people don't realize just how wonderful Jesus is. Don't miss His free Gift. The link says it all.