I've been looking at an American Megatrends M758LMRE mobo, equipped with a Celeron 1100MHz CPU and 256MB of SDRAM. It was replaced because it just wouldn't behave and I've discovered that if I reset the CMOS by shorting out the appropriate pins it will go through the POST and let me into the BIOS to set it. Once it's been set (usually to the optimum defaults) it will no longer show the POST and just won't boot up until I reset the CMOS again. Sometimes it won't even power up at all - even with a new PSU attached - and I'll go away and leave it (for a few days usually - I have other things to do!) and then it powers up again and shows the first described behavior. Clearly there is something wrong with it but I've never come across behavior like this before. Has anyone else? Has anyone any idea what sort of fault might cause this?