386 will only POST on 2nd attempt

[FishFinger]

I have a 386 motherboard (a Shuttle HOT-307 according to TH99). If it's been powered off for more than a few minutes then the POST will hang after the memory count. Resetting will then make it POST normally and work perfectly the whole time it's powered up, but switch it off for more than 15 minutes or so and it'll hang again and need to be reset.

I've already tried a spare CPU and have swapped the memory, but neither made a difference. It has a new NiMH CMOS battery as well.

 

[Trixter]

My guess is that the capacitors on the motherboard are going bad and are taking longer to energize. Replacing them may help, but before you do this, you should remove everything from the system except the video card to ensure the behavior is consistent (ie. isn't caused by something else like a hard drive).